That is called impact crazing.
Some big and soft and squishy took it's best shot right in that area.
Really not a big deal, but ugly as hell.
As long as it is really firm when you press on it with a bit of force, it should be structurally sound.
Blacks and greys are the most brittle colors as far as gelcoat goes, so this is pretty common (I think it has to do with how hot it gets when in the sunlight).
Pretty straightforward fix. The entire surface needs to be ground down to good glass (the scary part) and then prepped to block it back straight after layering with new glass...This will be easier if planning on painting the entire boat (eliminates the need to match colors...)
If you just want to use the boat for now, I would recommend getting some polyester resin and some MEK and mix up a small batch and simply brush some thinned resin into the cracked area and sand it smooth. Maybe with some 400 grit and let her buck...
GT