‘Latimeria’ von Pablo Wendel.

The fishhook is tied to the helium balloon with a string. To ensure that it does not fly away, it is fastened just below the water surface with a knot to an anchor rope. The special knot (a so-called robber‘s knot) unties itself as soon as a fish bites into the hook, causing the balloon to rise to approx. 32,000 meters height.

Watch video here.