diff --git a/movement/io/load_masks.py b/movement/io/load_masks.py
new file mode 100644
index 000000000..a81fb889e
--- /dev/null
+++ b/movement/io/load_masks.py
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+"""Load segmentation masks and associated tracking data into ``movement``."""
+
+from pathlib import Path
+
+import dask.array as da
+import pandas as pd
+import xarray as xr
+
+from movement.utils.logging import logger
+
+
+def load_octron_bboxes(
+    file_path: Path | str,
+    extra_data_vars: bool = False,
+    fps: float | None = None,
+) -> xr.Dataset:
+    """Load bounding box data from an OCTRON CSV file.
+
+    Parameters
+    ----------
+    file_path : Path | str
+        Path to the OCTRON CSV file.
+    extra_data_vars : bool, optional
+        If True, loads additional metrics (e.g., eccentricity, solidity,
+        orientation) as extra data variables in the Dataset. Default is False.
+    fps : float, optional
+        The number of frames per second in the video. If None (default),
+        the ``time`` coordinates will be in frame numbers. If provided,
+        the ``time`` coordinates will be converted to seconds.
+
+    Returns
+    -------
+    xarray.Dataset
+        An xarray Dataset containing the tracking data.
+
+    """
+    file_path = Path(file_path)
+    if not file_path.exists():
+        raise logger.error(FileNotFoundError(f"File not found: {file_path}"))
+
+    df = pd.read_csv(file_path)
+
+    # Convert time coordinates if fps is provided
+    time_coords = df.index.values
+    if fps is not None:
+        time_coords = time_coords / fps
+
+    # Extract core bounding box coordinates
+    # Note: Assuming standard 'x', 'y', 'width', 'height' columns exist
+    core_vars = {
+        "bboxes": (
+            ["time", "individuals", "features"],
+            df[["x", "y", "width", "height"]].values.reshape(len(df), 1, 4),
+        )
+    }
+
+    ds = xr.Dataset(
+        data_vars=core_vars,
+        coords={
+            "time": time_coords,
+            "individuals": ["ind_0"],  # Placeholder for single individual
+            "features": ["x", "y", "width", "height"],
+        },
+    )
+
+    # Optimization: Load heavy extra metrics only if explicitly requested
+    if extra_data_vars:
+        for extra_col in ["eccentricity", "solidity", "orientation"]:
+            if extra_col in df.columns:
+                ds[extra_col] = (
+                    ["time", "individuals"],
+                    df[[extra_col]].values,
+                )
+
+    return ds
+
+
+def load_masks_from_zarr(
+    zarr_paths: dict[str, Path | str],
+    chunk_size: tuple[int, int, int] = (100, -1, -1),
+) -> xr.DataArray:
+    """Lazily load instance segmentation masks from Zarr files.
+
+    Ensures a lossless, memory-efficient boolean representation using Dask.
+
+    Parameters
+    ----------
+    zarr_paths : dict[str, Path | str]
+        A dictionary mapping individual names to their Zarr file paths.
+        Example: {"ind_0": "path/to/mask1.zarr"}
+    chunk_size : tuple of int, optional
+        Chunking strategy for Dask. Default chunks across time (100 frames),
+        keeping full spatial dimensions (-1, -1).
+
+    Returns
+    -------
+    xarray.DataArray
+        A lazily evaluated DataArray with dimensions
+        (time, individuals, x, y).
+
+    """
+    dask_arrays = []
+    individuals = list(zarr_paths.keys())
+
+    for ind in individuals:
+        path = Path(zarr_paths[ind])
+        if not path.exists():
+            raise logger.error(FileNotFoundError(f"Zarr not found: {path}"))
+
+        # Lazily reference the Zarr array, cast to bool to minimize memory
+        # Assuming the mask is stored under the default root
+        # or a specific array
+        arr = da.from_zarr(str(path)).astype(bool)
+        arr = arr.rechunk(chunk_size)
+        dask_arrays.append(arr)
+
+    # Stack individual mask arrays along a new 'individuals' axis (axis 1)
+    stacked_masks = da.stack(dask_arrays, axis=1)
+
+    mask_da = xr.DataArray(
+        stacked_masks,
+        dims=["time", "individuals", "x", "y"],
+        coords={"individuals": individuals},
+        name="segmentation_masks",
+    )
+
+    return mask_da