Cold-water swimming · UK & Ireland
The tide table won't tell you when it's safe to get in
It tells you how high the water is. What matters is when it stops moving. Swim Window finds the turn — slack water — for your bay, and sends it the evening before.
One bay free · one line a day · cancel in a click
How the window is found
Tidal current for your stretch of coast, not water height at the nearest port.
One · read the current
The turn between flood and ebb, where the current falls below the threshold you can swim against.
Two · find the slack
Bounded by sunrise, sunset and water temperature, so the window is one you would actually use.
Three · bound it
Why not a tide table
- High water at the port is not slack water in your bay. The gap runs to twenty minutes.
- You read the chart on the shingle, in the dark, with cold hands.
- The one number you need — how fast the water is moving — is the one it doesn't print.
Current, not height
Tide tables answer a shipping question: will there be enough water under the keel. Swimmers have a different one: will the water take me somewhere I didn't plan to go. That is current, and it peaks and vanishes on its own schedule.
Known the night before
The window arrives while you are still indoors, not while you are standing on the shingle deciding.
One number, not a chart
A start time and an end time. Nothing to interpret and nothing to convert.
Always shows its reason
Every window says why it is where it is, so you can disagree with it and stay home.
What's in it
Slack water, not tide height
Per bay, not per port
Water temperature alongside
Bounded by sunrise and sunset
One evening email
Every window shows its reason
Price
One bay
Free, permanently. The bay you swim in most.
Every bay
£3 a month. As many stretches of coast as you swim.
Cancel in one click. The free bay keeps working afterwards.
Questions
I already check a tide table. What does this add?
A tide table gives height. Height does not tell you whether the water will carry you sideways. Slack water — the turn between flood and ebb — is when the current is at its weakest, and it does not line up neatly with the numbers on a tide table.
Is this safety advice?
No. It is one input. Wind, swell, run-off after rain and your own condition are not in it, and no model replaces looking at the water before you get in.
Why per bay and not per port?
Ports are where the gauges are. Swimmers are in bays, headlands and estuary mouths, where the turn can run twenty minutes off the port figure.
What arrives in the email?
One line the evening before: the window, the water temperature and the reason the window is where it is. Nothing else.
What if there is no window tomorrow?
The email says so, and says why — the turn falls in the dark, or the current never drops far enough. A day without a window is information too.
Tomorrow's window, tonight
Pick your bay. The first one is free and stays free.
Cancel in a click · no app to install