diff --git a/build.rs b/build.rs
index df8020a..850c71d 100644
--- a/build.rs
+++ b/build.rs
@@ -1,5 +1,5 @@
 use std::fs;
-use std::io::{Read, Seek, Write};
+use std::io::{Read, Write};
 use std::path::Path;
 use std::fs::File;
 use image::GenericImageView;
@@ -78,7 +78,10 @@ fn write_sim_data() {
 
     println!("cargo::rerun-if-changed={}", gps_input.to_str().unwrap());
     if !gps_output.exists() || gps_output.metadata().unwrap().modified().unwrap() < gps_input.metadata().unwrap().modified().unwrap() {
+        let mut gps_data = Reader::from_reader(File::open(gps_input.clone()).unwrap());
+        let record_count = gps_data.records().count() as u32;
         let mut gps_data = Reader::from_reader(File::open(gps_input).unwrap());
+
         let headers = gps_data.headers().unwrap();
         let (timestamp_idx, lat_idx, lon_idx) = (
             headers.iter().position(|x| { x == "seconds_elapsed" }).unwrap(),
@@ -86,6 +89,7 @@ fn write_sim_data() {
             headers.iter().position(|x| { x == "latitude" }).unwrap(),
         );
         let mut gps_output = File::create(gps_output.clone()).unwrap();
+        rmp::encode::write_array_len(&mut gps_output, record_count).unwrap();
         let mut last_stamp = 0.0;
         for record in gps_data.records().flatten() {
             let (timestamp, lat, lon) = (
@@ -113,8 +117,12 @@ fn write_sim_data() {
         }
     };
     if rebuild_motion {
-        let mut accel_data = Reader::from_reader(File::open(accel_input).unwrap());
+        let mut accel_data = Reader::from_reader(File::open(accel_input.clone()).unwrap());
         let mut gyro_data = Reader::from_reader(File::open(gyro_input).unwrap());
+
+        let record_count = accel_data.records().count() as u32;
+        let mut accel_data = Reader::from_reader(File::open(accel_input).unwrap());
+
         let headers = accel_data.headers().unwrap();
         let (timestamp_idx, accel_x_idx, accel_y_idx, accel_z_idx) = (
             headers.iter().position(|x| { x == "seconds_elapsed" }).unwrap(),
@@ -131,6 +139,7 @@ fn write_sim_data() {
         );
 
         let mut motion_output = File::create(motion_output.clone()).unwrap();
+        rmp::encode::write_array_len(&mut motion_output, record_count).unwrap();
         let mut last_stamp = 0.0;
         for (accel_record, gyro_record) in accel_data.records().flatten().zip(gyro_data.records().flatten()) {
             let (timestamp, accel_x, accel_y, accel_z) = (
@@ -162,6 +171,10 @@ fn write_sim_data() {
     // GPS data = 2, motion data = 1
     
     let mut unified_fd = File::create(unified_output.clone()).unwrap();
+
+    // Write out the stream index, which will be 2 (motion + gps)
+    rmp::encode::write_array_len(&mut unified_fd, 2).unwrap();
+
     let mut motion_output = File::open(motion_output).unwrap();
     let mut gps_output = File::open(gps_output).unwrap();
     rmp::encode::write_ext_meta(&mut unified_fd, motion_output.metadata().unwrap().len() as u32, 1).unwrap();
diff --git a/src/bin/main.rs b/src/bin/main.rs
index 2d8cd0b..de55a67 100644
--- a/src/bin/main.rs
+++ b/src/bin/main.rs
@@ -130,15 +130,9 @@ async fn main(spawner: Spawner) {
         let mut storage = SharedFlash::new(FlashStorage::new());
         let mut buf = [8; 1024];
         let partitions = esp_bootloader_esp_idf::partitions::read_partition_table(&mut storage, &mut buf).unwrap();
-        let data_partition = partitions.find_partition(
-            esp_bootloader_esp_idf::partitions::PartitionType::Data(
-                esp_bootloader_esp_idf::partitions::DataPartitionSubType::Undefined
-        )).expect("Unable to read partition table").expect("Could not find data partition!");
-        let data_offset = data_partition.offset() as usize;
-        info!("Loading simulation data starting at {data_offset:#02x}");
-        for sim_data in SimDataTable::open(storage.clone(), data_offset) {
+        for sim_data in SimDataTable::open(storage, partitions).expect("Could not find partition for sim data!") {
             info!("Found simulation data for {:?}", sim_data.srcid());
-            if spawner.spawn(renderbug_embassy::tasks::simulation::simulation_task(sim_data, garage.motion.dyn_sender())).is_err() {
+            if spawner.spawn(renderbug_embassy::tasks::simulation::simulation_task(sim_data, measurements.dyn_sender())).is_err() {
                 error!("Unable to spawn simulation task! Increase the task pool size.");
             }
         }
diff --git a/src/events.rs b/src/events.rs
index 65a2596..dd6feca 100644
--- a/src/events.rs
+++ b/src/events.rs
@@ -43,7 +43,8 @@ pub enum Measurement {
     SensorHardwareStatus(SensorSource, SensorState),
 
     // Simulation metadata updates
-    SimulationProgress(SensorSource, Duration, f32)
+    SimulationProgress(SensorSource, Duration, f32),
+    Annotation
 }
 
 #[derive(Clone, Copy, Debug)]
@@ -83,27 +84,30 @@ pub enum Telemetry {
 // GPS data = 2, motion data = 1
 #[derive(Debug, EnumSetType, Enum)]
 pub enum SensorSource {
-    Unknown = 0,
     // Real hardware
     IMU = 1,
     GPS = 2,
 
     // Fusion outputs
-    GravityReference,
+    GravityReference = 100,
     ForwardsReference,
     Location,
 
     // Simulated sensors
     Demo,
-    Simulation
+    Simulation,
+    Annotations = 3
 }
 
-impl From<i8> for SensorSource {
-    fn from(value: i8) -> Self {
+impl TryFrom<i8> for SensorSource {    
+    type Error = ();
+    
+    fn try_from(value: i8) -> Result<Self, Self::Error> {
         match value {
-            1 => SensorSource::IMU,
-            2 => SensorSource::GPS,
-            _ => SensorSource::Unknown
+            1 => Ok(SensorSource::IMU),
+            2 => Ok(SensorSource::GPS),
+            3 => Ok(SensorSource::Annotations),
+            _ => Err(())
         }
     }
 }
diff --git a/src/tasks/motion.rs b/src/tasks/motion.rs
index 54683fc..c0f85d1 100644
--- a/src/tasks/motion.rs
+++ b/src/tasks/motion.rs
@@ -29,6 +29,7 @@ pub async fn motion_task(src: DynamicReceiver<'static, Measurement>, ui_sink: Dy
                 ui_sink.publish(Notification::SensorStatus(source, state)).await;
             },
             Measurement::SimulationProgress(source, duration, _pct) => debug!("{source:?} simulation time: {}", duration.as_secs()),
+            Measurement::Annotation => ()
         }
     }
 }
\ No newline at end of file
diff --git a/src/tasks/simulation.rs b/src/tasks/simulation.rs
index efe61cd..7be9f26 100644
--- a/src/tasks/simulation.rs
+++ b/src/tasks/simulation.rs
@@ -1,17 +1,19 @@
 use core::cell::RefCell;
 use core::fmt::Formatter;
 
-use alloc::rc::Rc;
+use alloc::{collections::btree_map::Range, rc::Rc};
 use embassy_sync::channel::DynamicSender;
 use embassy_time::{Duration, Timer};
 use embedded_storage::{ReadStorage, Storage};
+use esp_bootloader_esp_idf::partitions::{PartitionEntry, PartitionTable};
 use esp_storage::FlashStorage;
 use nalgebra::{Vector2, Vector3};
 use log::*;
-use rmp::decode::{RmpRead, RmpReadErr};
+use rmp::decode::{DecodeStringError, RmpRead, RmpReadErr, ValueReadError};
 
 use crate::events::{Measurement, SensorSource, SensorState};
 
+#[derive(Debug)]
 pub struct SharedFlash<S> {
     storage: Rc<RefCell<S>>
 }
@@ -51,85 +53,168 @@ impl<S: ReadStorage> ReadStorage for SharedFlash<S> {
 }
 
 pub struct SimDataTable<S> {
-    storage: S,
-    reader: OffsetReader<S>,
+    reader: RangeReader<S>,
+    count: usize,
+    index: usize
 }
 
-impl<S: ReadStorage + Clone> SimDataTable<S> {
-    pub fn open(storage: S, offset: usize) -> Self {
-        debug!("Opening simulation data at {offset:#02x}");
-        Self {
-            reader: OffsetReader::new(storage.clone(), offset),
-            storage
+impl<S: ReadStorage + Clone> SimDataTable<S> where S::Error: core::fmt::Debug {
+
+    pub fn open(storage: S, partitions: PartitionTable<'_>) -> Result<Self, SimDataError<S>> {
+        let partition_type = esp_bootloader_esp_idf::partitions::PartitionType::Data(
+                esp_bootloader_esp_idf::partitions::DataPartitionSubType::Undefined,
+        );
+        info!("Searching for sim data partition");
+        let data_partition = partitions.iter().find(|partition| {
+            partition.partition_type() == partition_type && partition.label_as_str() == "sim"
+        }).expect("Unable to locate 'sim' data partition!");
+
+        let start = data_partition.offset() as usize;
+        let end = data_partition.len() as usize + start;
+        info!("Opening simulation data at {start:#02x}:{end:#02x}");
+        let mut reader = RangeReader::new(storage.clone(), start, end);
+        if let Ok(count) = rmp::decode::read_array_len(&mut reader) {
+            info!("Found {count} streams of simulation data");
+            Ok(Self {
+                reader,
+                count: count as usize,
+                index: 0
+            })
+        } else {
+            error!("Stream index is missing! Have you flashed the partition yet?");
+            Err(SimDataError::StreamIndexMissing)
         }
     }
 }
 
-impl<S: ReadStorage + Clone> Iterator for SimDataTable<S> {
+impl<S: ReadStorage + Clone + core::fmt::Debug> Iterator for SimDataTable<S> where S::Error: core::fmt::Debug + 'static {
     type Item = SimDataReader<S>;
 
     fn next(&mut self) -> Option<Self::Item> {
-        if let Ok(this_type) = rmp::decode::read_ext_meta(&mut self.reader) {
-            debug!("Found type={this_type:?} offset={:#02x}", self.reader.pos());
-            let start_pos = self.reader.pos();
-            self.reader.offset += this_type.size as usize;
-            match this_type.typeid.into() {
-                SensorSource::Unknown => panic!("Unsupported sensor type"),
-                srcid => Some(SimDataReader::open(self.storage.clone(), start_pos, srcid))
-            }
-        } else {
+        if self.index >= self.count {
             None
+        } else {
+            loop {
+                match rmp::decode::read_ext_meta(&mut self.reader) {
+                    Ok(this_type) => {
+                        let sensor_reader = self.reader.subset(this_type.size as usize);
+                        self.reader.seek(this_type.size as usize);
+                        self.index += 1;
+                        debug!("Found type={this_type:?}");
+                        match this_type.typeid.try_into() {
+                            Err(()) => error!("Found unknown simulation data chunk {this_type:?}"),
+                            Ok(srcid) => return Some(SimDataReader::open(sensor_reader, srcid))
+                        }
+                    },
+                    Err(err) => {
+                        error!("Read error while decoding simulation data {err:?}");
+                        return None;
+                    }
+                }
+            }
         }
     }
 }
 
-struct OffsetReader<S> {
+#[derive(Debug)]
+pub struct RangeReader<S> {
     storage: S,
+    start: usize,
+    end: usize,
     offset: usize
 }
 
-impl<S: ReadStorage> OffsetReader<S> {
-    pub const fn new(storage: S, offset: usize) -> Self {
+impl<S: ReadStorage> RangeReader<S> {
+    pub const fn new(storage: S, start: usize, end: usize) -> Self {
+        assert!(start <= end);
         // TODO: Should add bounds checking since we will know the size of the chunk already
         Self {
             storage,
-            offset
+            start,
+            end,
+            offset: 0
         }
     }
 
-    pub const fn pos(&self) -> usize {
-        self.offset
+    pub fn seek(&mut self, offset: usize) {
+        self.offset += offset;
+    }
+
+    pub fn subset(&self, size: usize) -> Self where S: Clone + core::fmt::Debug {
+        trace!("subset {:#02x}:{:#02x} -> {:#02x}:{:#02x}", self.start, self.end, self.start + self.offset, self.start + self.offset + size);
+        assert!(self.start + self.offset + size < self.end);
+        Self {
+            storage: self.storage.clone(),
+            start: self.offset + self.start,
+            end: self.start + self.offset + size,
+            offset: 0
+        }
     }
 }
 
-impl<S: ReadStorage> RmpRead for OffsetReader<S> {
-    type Error = RmpErr;
+impl<S: ReadStorage> RmpRead for RangeReader<S> where S::Error: core::fmt::Debug + 'static {
+    type Error = RangeReadError<S::Error>;
 
     fn read_exact_buf(&mut self, buf: &mut [u8]) -> Result<(), Self::Error> {
-        match self.storage.read(self.offset as u32, buf) {
-            Ok(_) => {
-                self.offset += buf.len();
-                Ok(())
-            },
-            _ => Err(RmpErr{})
+        let pos = self.start + self.offset;
+        if pos > self.end {
+            Err(RangeReadError::OutOfData)
+        } else {
+            assert!(pos + buf.len() <= self.end);
+            match self.storage.read(pos as u32, buf) {
+                Ok(_) => {
+                    self.offset += buf.len();
+                    Ok(())
+                },
+                Err(err) => Err(RangeReadError::Storage(err))
+            }
         }
     }
 }
 
 
 pub struct SimDataReader<S> {
-    reader: OffsetReader<S>,
+    reader: RangeReader<S>,
     srcid: SensorSource,
-    runtime: Duration
+    runtime: Duration,
+    event_count: usize,
+    index: usize
 }
 
-impl<S: ReadStorage> SimDataReader<S> {
-    pub fn open(storage: S, offset: usize, srcid: SensorSource) -> Self {
-        debug!("Opening {srcid:?} sim data chunk at {offset:#02x}");
+#[derive(Debug)]
+pub enum SimDataError<S: ReadStorage> where S::Error: core::fmt::Debug + 'static {
+    StreamIndexMissing,
+    InvalidChunkSize { expected: usize, found: usize },
+    MissingTimecode,
+    BadString,
+    DecodeError(ValueReadError<RangeReadError<S::Error>>),
+    EndOfStream
+}
+
+impl<S: ReadStorage> From<ValueReadError<RangeReadError<S::Error>>> for SimDataError<S> where S::Error: core::fmt::Debug {
+    fn from(value: ValueReadError<RangeReadError<S::Error>>) -> Self {
+        SimDataError::DecodeError(value)
+    }
+}
+
+
+impl<S: ReadStorage> From<DecodeStringError<'_, RangeReadError<S::Error>>> for SimDataError<S> where S::Error: core::fmt::Debug {
+    fn from(value: DecodeStringError<'_, RangeReadError<S::Error>>) -> Self {
+        SimDataError::BadString
+    }
+}
+
+impl<S: ReadStorage> SimDataReader<S> where S::Error: core::fmt::Debug + 'static {
+    pub fn open(mut reader: RangeReader<S>, srcid: SensorSource) -> Self {
+        debug!("Opening {srcid:?} sim data chunk");
+        let event_count = rmp::decode::read_array_len(&mut reader).unwrap() as usize;
+        debug!("Found {event_count} events!");
         Self {
-            reader: OffsetReader::new(storage, offset),
+            reader,
             srcid,
-            runtime: Default::default()
+            runtime: Default::default(),
+            event_count,
+            index: 0
         }
     }
 
@@ -137,48 +222,70 @@ impl<S: ReadStorage> SimDataReader<S> {
         self.srcid
     }
 
-    pub async fn read_next(&mut self) -> Result<Measurement, ()> {
-        match self.srcid {
-            SensorSource::IMU => self.read_motion().await,
-            SensorSource::GPS => self.read_gps().await,
-            srcid => unimplemented!("{srcid:?} is not a simulatable sensor!")
+    pub async fn read_next(&mut self) -> Result<Option<Measurement>, SimDataError<S>> {
+        if self.index < self.event_count {
+            self.index += 1;
+            // The read_* functions can only ever return a valid result, or a data/reading error, so we map them into a Some()
+            match self.srcid {
+                SensorSource::IMU => self.read_motion().await,
+                SensorSource::GPS => self.read_gps().await,
+                SensorSource::Annotations => self.read_annotation().await,
+                srcid => unimplemented!("{srcid:?} is not a simulatable sensor!")
+            }.map(|x| { Some(x) })
+        } else {
+            Ok(None)
         }
     }
 
-    fn verify_chunk_len(&mut self, length: u32) {
-        let chunk_len = rmp::decode::read_array_len(&mut self.reader).expect("Could not find the chunk length!");
-        assert_eq!(chunk_len, length, "Expected {length} fields but instead found {chunk_len}");
+    fn verify_chunk_len(&mut self, length: u32) -> Result<(), SimDataError<S>> {
+        let chunk_len = rmp::decode::read_array_len(&mut self.reader)?;
+        if chunk_len != length {
+            Err(SimDataError::InvalidChunkSize { expected: length as usize, found: chunk_len as usize })
+        } else {
+            Ok(())
+        }
     }
 
-    async fn read_delay_field(&mut self) {
-        let delay = embassy_time::Duration::from_millis((rmp::decode::read_f64(&mut self.reader).expect("Expected to find timestamp") * 1000.0) as u64);
+    async fn read_delay_field(&mut self) -> Result<(), SimDataError<S>> {
+        let timecode = rmp::decode::read_f64(&mut self.reader)?;
+        let delay = embassy_time::Duration::from_millis((timecode * 1000.0) as u64);
         self.runtime += delay;
-        Timer::after(delay).await
+        Timer::after(delay).await;
+        Ok(())
     }
 
-    async fn read_motion(&mut self) -> Result<Measurement, ()> {
-        self.verify_chunk_len(7);
-        self.read_delay_field().await;
+    async fn read_annotation(&mut self) -> Result<Measurement, SimDataError<S>> {
+        self.verify_chunk_len(3)?;
+        self.read_delay_field().await?;
+        let mut buf = [0; 256];
+        let msg = rmp::decode::read_str(&mut self.reader, &mut buf)?;
+        warn!("ANNOATION: {msg}");
+        Ok(Measurement::Annotation)
+    }
+
+    async fn read_motion(&mut self) -> Result<Measurement, SimDataError<S>> {
+        self.verify_chunk_len(7)?;
+        self.read_delay_field().await?;
         let accel = Vector3::new(
-            rmp::decode::read_f64(&mut self.reader).unwrap() as f32,
-            rmp::decode::read_f64(&mut self.reader).unwrap() as f32,
-            rmp::decode::read_f64(&mut self.reader).unwrap() as f32,
+            rmp::decode::read_f64(&mut self.reader)? as f32,
+            rmp::decode::read_f64(&mut self.reader)? as f32,
+            rmp::decode::read_f64(&mut self.reader)? as f32,
         );
         let gyro = Vector3::new(
-            rmp::decode::read_f64(&mut self.reader).unwrap() as f32,
-            rmp::decode::read_f64(&mut self.reader).unwrap() as f32,
-            rmp::decode::read_f64(&mut self.reader).unwrap() as f32,
+            rmp::decode::read_f64(&mut self.reader)? as f32,
+            rmp::decode::read_f64(&mut self.reader)? as f32,
+            rmp::decode::read_f64(&mut self.reader)? as f32,
         );
 
         Ok(Measurement::IMU { accel, gyro })
     }
 
-    async fn read_gps(&mut self) -> Result<Measurement, ()> {
-        self.verify_chunk_len(3);
-        self.read_delay_field().await;
+    async fn read_gps(&mut self) -> Result<Measurement, SimDataError<S>> {
+        self.verify_chunk_len(3)?;
+        self.read_delay_field().await?;
         let coords = Vector2::new(
-            rmp::decode::read_f64(&mut self.reader).unwrap(),
-            rmp::decode::read_f64(&mut self.reader).unwrap()
+            rmp::decode::read_f64(&mut self.reader)?,
+            rmp::decode::read_f64(&mut self.reader)?
         );
         
         Ok(Measurement::GPS(Some(coords)))
@@ -186,10 +293,13 @@ impl<S: ReadStorage> SimDataReader<S> {
 }
 
 #[derive(Debug)]
-pub struct RmpErr{}
-impl RmpReadErr for RmpErr {}
+pub enum RangeReadError<E> {
+    OutOfData,
+    Storage(E)
+}
+impl<E: core::fmt::Debug + 'static> RmpReadErr for RangeReadError<E> {}
 
-impl core::fmt::Display for RmpErr {
+impl<E> core::fmt::Display for RangeReadError<E> {
     fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
         f.write_str("RmpErr")
     }
@@ -203,8 +313,18 @@ pub async fn simulation_task(mut reader: SimDataReader<SharedFlash<FlashStorage>
     events.send(Measurement::SensorHardwareStatus(reader.srcid(), SensorState::Online)).await;
 
     // TODO: SimulationProgress updates
-    while let Ok(next_evt) = reader.read_next().await {
-        events.send(next_evt).await;
+    loop {
+        match reader.read_next().await {
+            Ok(Some(next_evt)) => events.send(next_evt).await,
+            Ok(None) => {
+                warn!("End of simulation data stream");
+                break
+            }
+            Err(err) => {
+                warn!("Error during sensor stream: {err:?}");
+                break
+            }
+        }
     }
 
     events.send(Measurement::SensorHardwareStatus(reader.srcid(), SensorState::Offline)).await;