Umm, non-painful water, like literally every official Sonic title ever. Getting out of water in time for a countdown when you have no air bubbles is a good enough motivator and scary enough as is, adding a constant need to collect rings after you're knocked back in the hurt animation in addition to NEEDING air bubbles is just over the top. When you're good enough at the stage, you should be able to breeze through sections like these. Instead, at any skill level, you're asking the player to have rings in the first place, jump in the water, get MORE rings quick enough so you don't die, and then run towards an air source because in the time it took you to find more rings you've been drowning this whole time.