diff --git a/sensor_msgs/CMakeLists.txt b/sensor_msgs/CMakeLists.txt
index 530141e3..d73084ac 100644
--- a/sensor_msgs/CMakeLists.txt
+++ b/sensor_msgs/CMakeLists.txt
@@ -18,6 +18,7 @@ find_package(rosidl_default_generators REQUIRED)
 find_package(std_msgs REQUIRED)
 
 set(msg_files
+  "msg/Altitude.msg"
   "msg/BatteryState.msg"
   "msg/CameraInfo.msg"
   "msg/ChannelFloat32.msg"
diff --git a/sensor_msgs/README.md b/sensor_msgs/README.md
index 7385aaad..5620b340 100644
--- a/sensor_msgs/README.md
+++ b/sensor_msgs/README.md
@@ -16,6 +16,7 @@ This package provides some common C++ functionality relating to manipulating a c
 * [point_field_conversion.hpp](include/sensor_msgs/point_field_conversion.hpp): A type to enum mapping for the different PointField types, and methods to read and write in a PointCloud2 buffer for the different PointField types.
 
 ## Messages (.msg)
+* [Altitude](msg/Altitude.msg): Single vertical position (altitude/depth) measurement.
 * [BatteryState](msg/BatteryState.msg): Describes the power state of the battery.
 * [CameraInfo](msg/CameraInfo.msg): Meta information for a camera.
 * [ChannelFloat32](msg/ChannelFloat32.msg): Holds optional data associated with each point in a PointCloud message.
diff --git a/sensor_msgs/msg/Altitude.msg b/sensor_msgs/msg/Altitude.msg
new file mode 100644
index 00000000..9d5f04a4
--- /dev/null
+++ b/sensor_msgs/msg/Altitude.msg
@@ -0,0 +1,34 @@
+# Single vertical position (altitude/depth) measurement.
+#
+# Units & sign (REP-103): meters, +Z up. Negative altitude indicates depth.
+#
+# Semantics (REP-105):
+# - 'altitude' is the height (or depth if negative) of the origin of header.frame_id,
+#   measured vertically in the selected 'reference'.
+# - header.frame_id identifies the point this measurement applies to.
+#
+# Reference:
+# The 'reference' field indicates what this measurement is relative to.
+#
+# Uncertainty:
+# - 'variance' is the measurement variance in m^2; 0.0 indicates unknown.
+
+# Reference enumeration
+uint8 REFERENCE_UNKNOWN=0
+uint8 REFERENCE_MSL=1            # altitude above mean sea level (as provided by the sensor/system)
+uint8 REFERENCE_WGS84=2          # altitude above WGS84 ellipsoid (matches NavSatFix semantics)
+uint8 REFERENCE_EGM96=3          # altitude relative to EGM96 geoid model
+uint8 REFERENCE_LOCAL_DATUM=4    # altitude relative to a publisher-defined local vertical datum
+uint8 REFERENCE_SURFACE=5        # altitude relative to a local physical surface (ground, seabed, water surface, etc.)
+
+# Timestamp and point of the measurement
+std_msgs/Header header  # stamp: measurement time; frame_id: measurement point
+
+# Scalar vertical position
+float64 altitude        # Vertical position in meters (+Z up); negative for depth
+
+# Measurement uncertainty
+float64 variance        # 0 is interpreted as variance unknown
+
+# Which reference 'altitude' is relative to (see REFERENCE_* constants above)
+uint8 reference