Submarines are Vehicle use in all AIKa R-16: Virgin Mission. They appear on the water as floating, Salvager-like devices, partially submerged under the ocean. Each submarine is different in each series. In AIKa R-16: Virgin Mission Eri Shinkai uses one to help explore the oceans to find the mystery. Later Aika Sumeragi] must generally defeat all the enemies, while trying to save her friends in Deep Blue Girl.
Salvager similar devices.