hermosa freja recuerdo que durante años veia sus fotos tenia los videos era su fan de verdad amaba su rostro sus expresiones su sonrisa su seredad su voz y movimientos
That's for measuring body density. When you're in a sea water, that should be the line of water level. If you get too dense, you won't float as much as you should, and water may come up to the chin or the ears.