The water rush makes the noise
no
The water hitting the ground.
all bras are water resistant!
No
From the water crashing down on the sand.
Could be hydraulic shock (water hammer)
Push-up bras or wired bras. Even bras that are too small for you will work., but I use push-up bras.you could try a water bra too.
Techniqually it shouldn't, so no.
Evaporation of water hasn't an acoustic effect; for boiling the answer is yes.
it may be getting air in the system .
Gargle water in your mouth and that's the sound.