I don't think you ever played Ranger 2 with its currents+Qwilfish maze. In Ranger 3 all they do is slow you down a bit, or maybe speed you up.Pokemon Ranger 3, Seas with currents. Nuff said
The steam vents on the other hand are really annoying. I lost half of my Styler energy when trying to climb up the submarine.
Also I like how in Ranger 3 you can just summon a Lati@s at will. I imagine most Gen 3 players would want to strangle the main character in this game, especially those that never managed to find their roaming Lati.