iOS, iPadOS, and macOS have a pretty great built-in background-noise generator these days. While lots of actual beaches can go dead silent and then have a loud wave crash in, the waves that
It’s available in Settings -> Accessibility -> Audio & Visual -> Background Sounds. You’ll have to download the sounds each once, but after that they stay on your device.
Digging this deeply in Settings isn’t pleasant if you just want some white noise, so you may want to add a control to Control Center like “Background Sounds” (way down in the Hearing Accessibility section) to turn the ocean noise on and off.
I turn this on my iPad when going to bed if I want to take extra steps to ensure that I don’t wake up in the middle of the night.