Just played this a bit, and I've got some notes for you:

• Where you moved the timer on the UI is hardly visible on an Index - I can see it's in the upper-left but I can't read it at all.
• The Respawn Collider is a bit low - I see the underside of the water before I respawn.
• The second checkpoint is rotated too far counter-clockwise, when I respawn I'm facing the wall instead of the floating boxes
• However you're doing the floating boxes affects the player's ability to jump, making it unpredictably difficult to jump from box to box.
• The music loop is very short, starts to grate on me after about 3 loops.
• Since you removed the on-screen display when the I grab power-ups, I don't know how much time I have left for jump power-ups to time my movement through the pillar jumps.
• There's not a great indication to the player that you will fall through the sand traps
• The boat geometry overlaps each other a bit when they pull up next to one another
• Your explanatory UI text bleeds through the world

Fun and environment and concept! Posting a pic showing the UI bleeding through along with my dismal time, the floating crates section really killed me.