diff --git a/my/core/__main__.py b/my/core/__main__.py
index 05f5a2c..dce646a 100644
--- a/my/core/__main__.py
+++ b/my/core/__main__.py
@@ -542,6 +542,14 @@ def query_hpi_functions(
                 pprint(item)
         else:
             pprint(list(res))
+    elif output == 'gpx':
+        from my.location.common import locations_to_gpx
+
+        # can ignore the mypy warning here, locations_to_gpx yields any errors
+        # if you didnt pass it something that matches the LocationProtocol
+        for exc in locations_to_gpx(res, sys.stdout):   # type: ignore[arg-type]
+            click.echo(str(exc), err=True)
+        sys.stdout.flush()
     else:
         res = list(res)  # type: ignore[assignment]
         # output == 'repl'
@@ -681,7 +689,7 @@ def module_install_cmd(user: bool, parallel: bool, modules: Sequence[str]) -> No
 @click.option('-o',
               '--output',
               default='json',
-              type=click.Choice(['json', 'pprint', 'repl']),
+              type=click.Choice(['json', 'pprint', 'repl', 'gpx']),
               help='what to do with the result [default: json]')
 @click.option('-s',
               '--stream',
diff --git a/my/location/common.py b/my/location/common.py
index fa8bdad..5c03d5e 100644
--- a/my/location/common.py
+++ b/my/location/common.py
@@ -1,5 +1,5 @@
 from datetime import date, datetime
-from typing import Union, Tuple, Optional
+from typing import Union, Tuple, Optional, Iterable, TextIO, Iterator
 from dataclasses import dataclass
 
 from my.core import __NOT_HPI_MODULE__
@@ -32,3 +32,48 @@ class Location(LocationProtocol):
     accuracy: Optional[float]
     elevation: Optional[float]
     datasource: Optional[str] = None  # which module provided this, useful for debugging
+
+
+def locations_to_gpx(locations: Iterable[LocationProtocol], buffer: TextIO) -> Iterator[Exception]:
+    """
+    Convert locations to a GPX file, printing to a buffer (an open file, io.StringIO, sys.stdout, etc)
+    """
+
+    try:
+        import gpxpy.gpx
+    except ImportError as ie:
+        from my.core.warnings import warn
+
+        warn("gpxpy not installed, cannot write to gpx. 'pip install gpxpy'")
+        raise ie
+
+    gpx = gpxpy.gpx.GPX()
+
+    # hmm -- would it be useful to allow the user to split this into tracks?, perhaps by date?
+
+    # Create first track in our GPX:
+    gpx_track = gpxpy.gpx.GPXTrack()
+    gpx.tracks.append(gpx_track)
+
+    # Create first segment in our GPX track:
+    gpx_segment = gpxpy.gpx.GPXTrackSegment()
+    gpx_track.segments.append(gpx_segment)
+
+
+    for location in locations:
+        try:
+            point = gpxpy.gpx.GPXTrackPoint(
+                latitude=location.lat,
+                longitude=location.lon,
+                elevation=location.elevation,
+                time=location.dt,
+                comment=location.datasource,
+            )
+        except AttributeError:
+            yield TypeError(
+                f"Expected a Location or Location-like object, got {type(location)} {repr(location)}"
+            )
+            continue
+        gpx_segment.points.append(point)
+
+    buffer.write(gpx.to_xml())
diff --git a/tox.ini b/tox.ini
index e3ff8f1..2809e3c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -85,6 +85,7 @@ allowlist_externals = cat
 commands =
     pip install -e .[testing,optional]
     pip install orgparse # used it core.orgmode?
+    pip install gpxpy # for hpi query --output gpx
 
     {envpython} -m mypy --install-types --non-interactive \
                     -p my.core \