It comes as a surprise to many people, but the sea off the south east of England is a perfectly decent temperature for swimming for at least three months of the year - from July to September - and some even swim as early as mid June. This section describes all the swimmable beaches within a day's rail trip from London, as well as the walks on this website that lead to them.

Some general tips are given below. For individual beaches, see the area menu at the top of this page.

When is it warm enough?

Sea warms up more slowly than air or land, and the best time for swimming lags a bit behind the best temperatures of summer. On a hot sunny day in June, the sea can look awfully enticing, but if you plunge in, you will find the water is icy cold - around 12-13 degrees early in the month, though this climbs to 15 or 16 degrees by its end. In July the sea temperature then climbs to around 18 or 19 degrees, and stays there throughout August.

By early September the sea temperature is declining slightly (though this has not been so true in recent years, maybe due to climate change), but more importantly the air temperature is lower and many people no longer think of going to the beach. The air temperature also has an effect on the temperature of the top layer of the sea. When days are longer and the sun is hotter, the upper 30 centimetres or so of the sea become a degree or two warmer. In September, as nights get longer and the air temperature cooler, this effect lessens. So a 18 degree sea can seem colder in September than than it does on a hot day in July. It is usually falling air temperature, rather than falling sea temperature, that brings an end to sea swimming for the year.

For the same reason, the sea tends to feel warmer later in the day than it does in the early morning (when the sun or air temperature has had less time to warm it up). If you go for two or three swims in a day, you will also find that your body becomes more accustomed to the sea temperature and it feels warmer as the day goes on. Strong sunshine can also warm your body as you swim, and on shallow beaches the sand or shingle may heat the incoming tide a bit on a hot day.

A harmless bit of sediment

The sea off the south coast is never clear - it always looks a bit murky. But this is sediment, not pollution. Look around you at the soft chalk cliffs or crumbling muddy shoreline and you will understand why the English Channel is not as clear as the sea off Cornwall. But actually bathing water standards are pretty stringent these days, and nearly all south coast beaches meet rigorous water hygiene standards.

A rare occasion when water quality can be an issue is after really heavy rains, when sewage treatment plants get overwhelmed and raw sewage is discharged into the sea. At such times, the Surfers Against Sewage website can be a good way to check the status of your local beach. But even if there is an issue, it usually only lasts for a day or so, until the tide washes the discharge away.

  • If sediment in the water bothers you particularly, try and swim at high tide, when fresh clean water has flowed in from the open sea. By contrast, just after low tide, the water can be positively brown (due to stirred up sediments) on beaches with a long, flat bottom.
  • Though rich in marine life (see the enormous cuttlefish that sometimes wash up on beaches, having come from the deep ocean to breed in our waters and then die) the sea off the south coast seems relatively free of any creatures that bother humans. You get the occasional story in the newspapers about exotic foreign jellyfish being seen off the coast of Devon, but the author has been swimming in the Channel for years and has never heard of anyone being bitten, stung or stabbed by anything. If you are worried about this, however, wearing swimming shoes (see below) offers some reassurance.

Handy tips

  • South coast beaches are - with a few exceptions - shingle (ie pebble) beaches, so walking down to the water's edge - or more to the point, getting out of the sea - can be a painful business if you are barefoot. A pair of rubber-soled swimming shoes is the easy solution, available for around £5-6 from beach shops, sports shops, or anywhere that sells diving equipment.
  • Don't go out of your depth unless you are a confident swimmer, and before you do go too far into deeper water, check the way the currents are flowing (which you can do by staying still, and seeing which way you move in relation to objects on the shore, such as the place you left your clothes). Fortunately, currents tend to be flowing parallel to the shore on the south coast - broadly, they go up the Channel (ie eastwards) when the tide is rising, and down the Channel (westwards) when it is ebbing. Note that currents can be stronger further away from the shore, however, and avoid the mouths of rivers.
  • It is useful to know the state of the tide before you swim, especially on beaches with long flat sections where the sea can come in or go out rapidly. Information on high and low tides up to six days ahead can be found on the BBC weather website.
  • To check how big the waves will be before you head to the beach, check out this website, or see the beach forecasts available for some resorts on the Met Office website. Anything under 0.4 metres is usually not an issue.