Terrain Altitude don't have seabed data.

[patrickelectric]

[jaxxzer]

@patrickelectric can you explain the problem? It's not clear.

[patrickelectric]

waypoints altitude in the ocean is zero and not the real depth of the point under the sea. Terrain Altitude should be able to display how deep the vehicle can go before hitting something, like with aerial vehicles.

[jaxxzer]

Waypoints in the ocean are 3d with absolute depth. Altitude above terrain reference frame for mission items is not supported by ardusub, only absolute altitude.

[patrickelectric]

This is a QGC feature and not ArduSub.