That seashell/ocean hiss is Suno misreading something in your prompt as water or air — usually a reverb or atmosphere word — and rendering literal rushing noise under the track.
1. Hunt the water words. Ethereal, airy, atmospheric, washed, waves, floating, dreamy reverb — any of these can spawn the hiss. Cut or replace the most likely one and regenerate.
2. Exclude it directly: hissing, rushing water, ocean sounds, white noise, wind noise in the Exclude field.
3. Describe dry instead of atmospheric. clean dry studio recording, tight, no reverb wash gives you space without inviting the ocean.
4. If it's only in one section, Replace Section on that part — the hiss often comes from a single bracket's wording.
5. Stems rescue: if the song is otherwise perfect, Get Stems and check which stem carries the hiss (usually pads/FX). Mute or EQ it — high-pass the offending stem and the seashell drains away.
The hiss is almost always one guilty word. Find it, kill it, and it won't come back.
Good luck! Hank founder of SonorixPG