I have tried to import bathymetry in OSM format via the OSM import node form the GameDev tools. The .osm file I use, is generated by this tool:
Srtm2Osm [wiki.openstreetmap.org]
It is an area of 50km around south Oahu

The general shape seems to be correct, but it is way to small and in a really wired position around X:between 5570 and 5620 Y: between -39220 and -39270.
May be the .osm file is missing some attributes, the script needs, to scale it correctly and center it in the scene?
, it is really a steep learning curve, but def. worth it!