"Under Water" from "Phalanx". Composed by S. Yamaguchi.
This is my favourite track from the 1992 shoot ‘em up “Phalanx” for the SNES. It’s kind of infamous for its weird box art in the US version, but thankfully Europe got a box with the same artwork as in the Japanese one (as seen in the video). I tried beating this game just recently, but couldn’t get past the “Destroyer”-level.