It may have been the second, which was the long corridor of different jumps. I had trouble balancing the last jump over the wall. The third one had a similar problem which was why the deeper pit was added to help jump up.
Overall, I never got the physics of the game to feel exactly how I wanted and so the puzzle design suffered. After the jam I'll be playing with settings to get something I'm more happy with. Possibly increasing the fish's speed, but also increasing linear dampening so you slow down faster. Maybe mess with turning differently when in water since I always found myself bumping into walls.
Thanks for playing the game and for the feedback!