Aquahav – the name is, of course, nonsense, but nothing else comes to mind.
Racial ability – Water Spout:
A water spout appears on the battlefield, sucking in everyone who gets too close. It also scatters debris and water around the battlefield, creating puddles and barricades – while the former can be overcome by the Atlanteans, the latter cannot be overcome by either side.
Special Ability – Wrath of Shalassa – allows you to flood a large area on the battlefield and on the global map for a certain period. Atlanteans pass through calmly, while the rest get stuck. You can also create a storm at sea.
Skills:
Tidal Wave – you can unleash a wave on an area of the map near the sea, dealing minor damage to the enemy army and slowing it down.
Whirlpool – creates a trap on the battlefield and on the global map that sucks in armies (on the global map) / units (on the battlefield), and it affects any units.
Third skill – ???
Regarding the commander, I suggest something like Sea Baron or Sea Wolf.