Whitewater and rivers

Siphon

Also: sieve, siphon between rocks

A siphon is a spot where water flows under or between rocks, but a person can't. Siphons are deadly traps.

You can often recognise them because water “disappears” without any visible outflow at the surface. In boulder-choked rivers, siphons often lie between large boulders. Keep well away from such spots, even as a swimmer.

Warning: siphons often can't be seen from above. Scout unknown spots and avoid areas where a lot of water flows in without visibly coming out again.