Originally posted by Chofa:

Im exploring a whole biome of swamp but I think some crypts should appear by now "but they dont".

Are they limited to 1 or 2 per biome?

It's all pretty random. I only found one in my first swamp, but then I set sail and found another conveniently located on the shoreline of another swamp biome. Once I cleared that I looked to my left and saw another not 20 yards away !! Random as Hell and totally unpredictable - it's what I absolutely love about this game. Nobody but nobody has the same experience as me - I literally never have a clue as to what I'll find over the next ridge or around the next corner.