If you dig an L shaped hole in the ground, put a slab in the corner of the L, waterlog it, and then, without auto-jump, let yourself flow towards the end of the L, you're going to start jumping. Also with the slab, doesn't matter which wall you touch you jump.

Works without the slab too. At the end of the L slightly press the jump button.

https://drive.google.com/file/d/1hGEXcNKwLaNF-2CFHUr2l3XO2B-OJS8K/view?usp=sharing