There are plenty of laws (in this case, more like 'treaties') regarding international waters and use thereof. You can't do whatever you like, you certainly can'

There are plenty of laws (in this case, more like 'treaties') regarding international waters and use thereof. You can't do whatever you like, you certainly can't avoid all laws there. Usually you will have to flag your structure as being part of a nation and then follow their laws while onboard.