What do you do if your house is going underwater at the ocean?

Either put your house on stilts. Jack it up and put stilts under it or move further inland onto higher ground.

Otherwise you could drown the next time there is a high tide or storm like a Hurricane or even a tornado.

However, I'm not sure how houses on stilts do in tornadoes, some of them might just fly away like Dorothy in her dream  in "The Wizard of OZ".