A tsunami crashes into the sun (breaking it in half) and creating a different wing of the tsunami all together. This wing crashes down and creates a lagoon.
This lagoon was created on purpose by a really angry dude and his catapult (かた). He wanted a nice place to lounge that's tropical, but not too bright. So he came up with a plan: use a giant catapult to send a tsunami into the sun!
Currently there are no similar looking kanji which exist in the WaniKani learning system