Very solid execution of a quite generic endless game. the controls feel good, the audiovisual presentation is quite nice and I like the little background story.
Though it creates a bit of ludonarrative dissonance with the goal being trying to collect plastic bottles to stay swimming as long as possible, especially with the game's name referencing Sisyphus. Story-wise swimming is meant to be the punishment. Or are you actually an advocate of Albert Camus conception of Sisyohus? In that case, I revoke my complaint.
Viewing post in The Myth of Fishyphus jam comments
The restart is not to keep him swimming but to punish him if he doesn't do it's job (collecting bottles). The title is mostly catchy and not to take too seriously, the only similarity to Sisyphus is just that they both have been punished eternally.
I appreciate that you took your time to play it and leave a comment, thanks!