Exo One - Darwin III IL Speedrun - 2m52s
Surfing is the way.
Much credit to ElectroLlama. I gave up on surfing in favor of underwater gliding a while back because it seemed way too unreliable, but he proved its worth in speed and made me reexamine the method.
The trick to surfing is getting enough speed and a good angle across the wave pattern. (And getting a feel for letting go of gravity only when you absolutely must.) Surfing is a lot faster than underwater gliding, but the speed is very spiky. While you can start surfing as soon as you're supersonic, having extra speed as a cushion helps immensely.
I try to get everything I can out of the first wind, and the angle to the powerup from rock at the end of the wind is surfing friendly. You can swing even more left past the rock, and it's a little faster to skip the powerup, but I keep grabbing it out of habit.
It's really hard to maintain speed over the bigger, later waves, but I found jumping off those bounces helps. I don't (consciously) jump off the water anywhere else in the level.