Ruined portal lets water through

In creative, scouting seed. First portal seen generated under water. 

Replaced missing pieces and crying obsidian, then used sand to surround it and create an air pocket within the frame. Each pre-existing piece of obsidian let water through like it wasn't there. Had to replace each one before portal would be dry enough to light.

Seed:   -718530799, co-ords in screenshots. There was no visual difference I could see.