Two Tides a Swingin'
A rather convoluted water-filled map, with the rhythm non-trivial to learn... but once you've got it down, this is a pretty cool map for medium to large groups. Lots of secrets, lots of acceptable strategies... nice construction (although on slower machines, it's a dog). Well worth the learning curve.
Levels in map "2 Tides a Swingin'":
Swinging Low