As stated, the GoPro is a "POV" video
camera. Just because it will take photos does not mean they will be good photos. ALthough is is more "camera style" than like a lipstick type cam, it's primary mission is video.
The wide, WIDE angle of these cams (in my opinion) is way more geared toward video, not photos. I certainly agree that for video they are pushing the wide FOV (field of view) a bit too far, especially for seascapes that are wide open with flat horizons.
These wide angle cams work better in close quarters to show the action going on around you - within 25 feet max IMO...
Great for MT biking, skiing, etc, but yes the distortion of the "flat" horizon is annoying. On a boat or kayak about the only view I use it for is from bow or stern looking at the crew... or from mast down.
You can reduce the effect of the horizon distortion by centering the view of the camera and splitting the horizon right in the middle of the FOV. Not a cure by any means, but it helps.
The older GoPro's had much less VOF, there are also other cams out there worth checking out too
Might see what's up over at HelmetCamReview.com