and he jumped into the billabong

you may jump into any natural body of water (pond, stream, lake, etc)  with an area of at lest 1m , melding yourself and all the equipment you carry with the water for the duration. Using your movement, you enter into the water at a point you can touch. Nothing of your presence remains visible or otherwise detectable by nonmagical senses.

While merged any Wisdom (Perception) checks you make to hear sounds outside it are made with disadvantage. You remain aware of the passage of time and can cast spells on yourself while merged with the water. You can use your movement to leave the water where you entered it, which ends the spell. You otherwise can't move.