I’d say gel applied when wet, sopping wet. Put it on upside down in the shower and use a T-shirt to wrap it and let it dry naturally either in bed or through the day. When it’s dry scrunch it with your hands.
If it’s not fine hair that usually works best my other curlies tell me. I have very fine curly hair so I just use a salt spray and a tiny bit of curl cream, but I go for a more beachy look as anything heavier and it’s basically just limp, wavy and looks greasy.