This is how it can be done now,
<animation>
<!-- by surface type, if you use this specifiy all that may make sense for this unit,
-- ie, for amphibious units all three,
-- for land units 'land' & 'fordable'
-- for any-water units 'fordable' and 'deep-water'
-- For units of field 'air' or 'deep-water' this makes no sense.
-->
<surface type="land" path="models/walking.g3d" />
<surface type="fordable" path="models/wading.g3d" />
<surface type="deep-water" path="models/swimming.g3d" />
<!-- all optional, played when changing from one surface type to another -->
<surface-change from="land" to"deep-water" path="models/dive.g3d" />
<surface-change from="fordable" to"deep-water" path="models/dive.g3d" />
</animation>
All skill stats are the same, including animation speed
But it is functional, if it gets implemented properly later (at least allowing different anim-speed, if not using seperate skills) and anyone uses this method, it can be 'translated' to the new system in the engine with ease.