I'm making Tideline: a free, open-air DJ set played on the bed of the River Thames at low water, where the tide decides when the music starts and when it has to stop.

Almost every sound I play arrived here by water. Jamaican dancehall and sound system culture, Nigerian afrobeats, South African amapiano — and the British music they became: jungle, UK garage, grime, afroswing. They came up this river into the docks with the people who carried them. London's dancefloors are a downstream effect of the Thames. Nobody says that out loud, and nobody stands on the riverbed to hear it.

So: one afternoon on a spring low water, I set up a battery-powered rig on the exposed foreshore below the river wall and play that story in order — the records that came off the boats, then the records London made out of them. No door, no bar, no guest list, no age limit, no venue. You come down the stairs off the river path. Bring your kids, bring your dog, stand in the shingle.

Then the tide comes back and takes the room away. A club night ends when the promoter says so. This one ends when the water says so — and the countdown is visible the entire time, creeping up the beach behind the decks. The set is written backwards from the tide table: I know to the minute how long I have, and the last record has to land as the shingle goes under.

Who benefits: whoever is on the river that afternoon. The foreshore is free and public, so this reaches the people nightlife prices out — under-18s, families, people who don't drink, people who don't have £25 for a door. Most Londoners only ever look at the Thames. Standing on it, with bass moving through it, is a different relationship.

I'll film it and release it free, so the river gets the credit and DJs elsewhere can steal the idea. Every tidal city has a foreshore.

The date is tide-led: an afternoon spring low water, set from the tide table once Port of London Authority consent is in place. The river picks the date, not me. That's the point.