Deckard relaxed and let the current carry him.

Exhaling, bubbles escaped from around the air regulator he held in his mouth.  The kelp was swept back, nearly horizontal with the sandy bottom in the strong current.  His muscles were relaxed as he hung suspended in the clear blue water.  Above him, ripples of yellow sunlight glimmered and cast shadows in the shallow water.

He swam underwater through the channel between two small islands.  As the ocean forced itself through the channel, it created an extremely swift current.  At times it was like being in a liquid treadmill as Deckard kicked with his fins but made no forward progress.  Having SCUBA dived all the way upstream to the edge of the islands, he now relaxed and let the current carry him back.

The water between the two islands was shallow, maybe twenty five feet deep but with visibility that went out one hundred feet in any given direction.  Now he was slowly sinking towards the bottom.  Just beneath him, sand and shattered sea shells were blown with the current like tumbleweed in the desert.  He inhaled, filling his lungs with oxygen.  The added buoyancy was just enough for him to pop back up and rise above the sandy surface.

Small fish darted around looking for food but there was little to be found.  They were fighting the current as Deckard had been, but were somewhat better suited for it.

The ocean blasted him back in the direction he had come, a half hour of swimming upstream was now a four-minute trip downstream as the horizons stayed neutral and the ocean bottom raced by below him.

Finally, he was alone.

Ten minutes later, he surfaced above the choppy waves.  The wind was coming in strong, so Deckard kept his regulator in his mouth as he bobbed on the surface and kicked his way to the shore.  Once he could touch the bottom, he took off his fins and snorkel, then walked in to the beach.