This is of a type I have wanted for some time: a water-based where aquatics figures can swim under a ship. The top portion is the ship itself (the amphibious assault ship the USS Tarawa (LHA-1), as a matter of fact), with some appropriate aircraft (a Harrier, three Blackhawks, and six Hueys) on the flight deck as hindering terrain, and the bridge as elevated and blocking terrain.
The bottom portion is the areas of the sea beneath the ship and the surface of the sea. A figure on the surface of the sea (as marked in dark blue) can 'descend' to the lower sea as part of its regular movement. The hindering terrain under water even effects aquatic figures, who need to slow in it and have a harder time seeing, after being on the bright surface. Landhuggers can get by on this map, but they are going to be pretty badly outclassed by aquatic or even flying figures.