The Island with Bear Grylls has got to be the most dangerous reality show on TV, and this clip just about proves it.

In this exclusive preview for RadioTimes.com, islander Frank makes the silly decision to cross a tidal channel by himself. Bordering on exhaustion and with deadly currents flowing under the water, it's a lethal combination and it takes just moments before Frank's sent drifting rapidly off course.

“It only takes seconds to drown,” warns Bear as Frank gets caught in a current and it looks like he’s going to be swept out to sea.

The group back on shore shout at him: “You’re going to have to kick a bit harder Frank, you’re drifting fast!”

A panicked Frank then hollers back that the tide’s taking him out as we see him careering down the channel. But what happens next? You’ll have to wait until Sunday to find out…

The Island with Bear Grylls returns on Sunday 23rd April at 9pm on Channel 4