I remembered seeing this game as a kid, but the name sounded off... And Wikipedia reveals it was released in North America (NTSC format) as "Shipwreckers!"[1]. It also featured 5-player local multiplayer if you had multitap, according to the article, and I remember most other games of the era supporting at most 4 players locally. I'll have to find this one and give it a try!

[1]: https://en.wikipedia.org/wiki/Overboard!_(1997_video_game)