divineing? yes. more mobs ? yeah easy to add even on existing biomes. an actual BOSSfight? not really. with the current boat repair mechanics a boss purely on water just wouldnt work. it would be a dps race boss. kill it before it kills your boat. boring.

they could add the kraken as a regular high threat enemy of course.

underwater BASE BUILDING? thats not gonna happen dude. they would have to redesign the entire building and raid event concept for just that.

ocean wont be a full scale biome like the others. which makes perfect sense.

i hope we get a new ship already with mistlands upgrade patch. a ship with a ballista and a lantern on it. maybe even with 2 sails. its overdue to get a bigger boat as jaws has put it. something like an roman galleon would still fit nicely.

but adding some more monsters to the ocean is a given i think. but not an actual full scale boss fight. maybe a giant shark. or an angry leviathan.

and more rare fish types of course. its the ocean afterall.

but dont expect a full fledged biome. thats what ashlands and deep north are for. i also doubt ashlands will add another new building material like mistlands did with black marble. would be too early for new material already.

if they add another structure material for entire base builds it wont be until deep north comes and it would be the last one. no it wont be steel. that would be lame.