My Kraken seems to be benefiting from LAND based promotion choices, not SEA based promotion choices. eg. "Hills and Forest Defence" and "Mobility I" rather than the naval version with the pointy hand and * graphic. It's an odd hybrid as it seems to be able to be summoned on land (by placing the summoner on a coast tile), but it can only move on the water. Not sure if this upgrade choice thing is unavoidable as a result of that, but I thought I'd report it anyway.