Skyboxes, sea, horizons

I’ve been messing around with a few beginner maps now and one thing I have noticed is that my horizons and skyboxes do not look anywhere near as good as real games, with obvious lines separating the sea and the skybox, and the higher up the map you travel the skybox separates from the sea leaving a gap! See screenshot



How do you go about recreating a sea horizon like what is seen in The Forest for example; something where the sea stretches out to the horizon (without rendering it all obviously) and seems to merge with the skybox so that no matter how high you climb (within reason) it “works”?
Basically how would I go about creating something like this:

http://upload.wikimedia.org/wikiped...neville-Carteret,_Basse-Normandie,_France.jpg

Also do you need any special software to create a skybox or just something like Gimp?

 

Hi Synapse11,

(Disclaimer: I'm no expert in this area.)
Assuming the player must stay on the ground/land, I'd probably look at a skybox that has no mountains at all but matches the sea's colour where it meets the sea.

Some questions: How close will you let the player get to the edges of your map? Can they go beyond the edge of what is shown? Can they fly and cross the sea or are they limited to land? How high can they go?

If you had enough distance to the edge of the map, you could then add in some small 3D or 2D mountains near the edge of the map for 'forced perspective' (but be aware this will look more fake the higher you go). There is also the issue you may not see them if the draw distance is too far. There are other more advanced ways to deal with this, it depends how much value that adds to your play experience.