Waterlog Reswum 
Great Ouse at Denver Sluice – swimming through silt
“Just downstream from Denver Sluice, a gigantic arrangement of lock gates that controls the main outlet of the Fen river system, I swam the Great Ouse, which runs out to the sea at King’s Lynn.”
Our bags heavy with wet swimming gear, Well Creek and Middle Level Main Drain behind us, Tim and I drive east to Salters Lode and a date with Denver Sluice. Crossing Well Creek, we walk along the high levee holding back the Old Bedford River, the water raging in the distance as the vast sluice gate holds back the streams and channels of this flat, reclaimed place.
The banks here are steep and swimming seems impossible. And so we double back, past the lock at the start of Well Creek and on to the tidal reaches of the Great Ouse. A muddy beach on the far side is calling us, but there’s no way of crossing the river here other than swimming. And so we alight on a grassy spot, drop our kit and weigh up our options.
Fresh reeds are poking up through what looks like quick, slippery mud. There’s a small, promising inlet down to the water’s edge, where the riverbed quickly disappears in a brown, murky haze. After our Middle Level Drain dip, it looks like paradise.
I slip off my shoes, stifle a scream as I tread on a thistle, and begin dolling myself up in my already soaked wetsuit. It’s a deeply unpleasant experience, but one I know will let me float off downstream without losing all feeling in my lower limbs. The sun may be up, but there’s a sharp breeze, rivers still cold after six months of low temperatures and incessant rain.
I slide myself down the bank on my backside, my neoprene boot sinking as soon as it hits the mud. I make a slip–sliding entrance and am am out of my depth within one step. I let the Great Ouse take me downstream, a gentle stroke pulling me on towards The Wash and away from Tim.
The water is absurdly muddy. I feel the gloop through my fingers in the shallows and see its grains as I slide my hands through the water. Roger said the Great Ouse was ‘grained with silt, like an old photograph’. It still is. He also reckoned this was what swimming in the Ganges was like. I can’t comment on that, but its shit brown colour reminds me of an ill–advised swim in the Mekong Delta in Vietnam while travelling a few years ago. Nothing but my fingertips were visible beneath the surface and the current yanked at me so strongly I feared I might be swept away.
The Great Ouse’s current may not be that powerful, but as I make a move to turn back, I feel its force. I am stuck stock still as I try and return to Tim, who by now is standing in the shallows, a slick mudslide showing where he made an unplanned entrance. I switch to a faster front crawl and am worn out when I reach him, just as he slips under. He too swims against the current, holding him static despite the push of his arms.
We linger on the bank, the late afternoon spring sunshine warming us as we discuss next swims, summer plans. Middle Level Drain’s industrial feel is so far from the Great Ouse’s natural whirl, despite their proximity. But surely, that’s what makes this dip so special. They compliment each other beautifully. We set off back to Salters Lode and the car, ready to take on the any swim Roger wants to throw at us.
Waterlog Reswum 
I’ve been following your swims for a while now, and this one sounds like one of the more unsettling. I find swimming through water weeds awkward enough. This one, silt combined with deceptive current, sounds unnerving.