Nice map theres lots to like about it. I'm not all that sure about the peaky wave things cos to me they looked a bit like mountains and I had to look several times to see whether I was looking at land or sea or whether the two were inverted. Maybe just keep the sea nice and simple. I would agree also with the rivers thing. Even if you have a big and magical spring in the middle of the landmass then there's a few other rivers joining between seas. Don't worry we get this a *lot* so much so we have river police now (look out for the badges like Ascensions). I'm not one so to try to help get you off the hook before they get mean and issue an arrest warrant, have a look over this tut.

http://www.cartographersguild.com/sh...he-right-place

Remember this is for real rivers - if your map uses other worldly effects then its fair game. Its your map.