Hampstead Heath Mixed Pond

Monthly water temperature temperature

The surface runs about 20 °C in August. The annual low is 5 °C in January and the high is 20 °C in July. No pronounced summer thermocline is recorded here. For October, the mean surface figure is 13.5 °C.

Mean water temperature by month (°C)

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
5	5	7	10.5	14.5	18	20	20	17.5	13.5	9.5	6.5

Safety safety

Tested weekly by the City of London Corporation for E. coli and intestinal enterococci, with results posted at the entrance. The pond is spring-fed from the Heath and has no sewage input; occasional algal blooms in a hot August can close it for a day or two.

Safety notes (3)

• The pond is unheated and open all winter. At 5 °C, a dip should last under 5 minutes for anyone without cold-water acclimatisation, and you should never swim alone in the winter months.
• The bottom is uneven and weedy in patches. The lifeguards ask that you stay inside the marked swimming area, which is clearly buoyed.
• There are fish, and occasional terrapins. Neither is dangerous; the real hazard is the cold and, after heavy rain, slipping on the jetty boards.

Where to get in

• Wooden jetty and ladder (male/female sides) — Two jetties with ladders into 0.8 m. The standard, and the only sensible entry when the water is under 10 °C.
• Grass bank step-in — Between the jetties in summer; the bank is muddy after rain and there is a 30 cm step down.

On site

• Changing rooms with hot showers (included in the entry fee)
• Sunbathing lawn and benches
• No car park; the nearest café is at the Parliament Hill lido, 12 minutes' walk

Getting there arrival · entry · exit

Getting there

Enter the Heath from the East Heath Road gate and follow the signs to the Mixed Pond: 10 minutes across open grass, uphill from the road. The entrance building contains the ticket desk, changing rooms and showers.

Go early. The pond opens at 07:00 and the first hour has the fewest people and the calmest water; by 10:00 on a hot weekend the queue for the changing rooms reaches the gate.

Getting in

Use the jetty ladder. It is safe, it is how the regulars enter, and it lets you lower yourself in rather than committing to a plunge.

The pond is 1.2 hectares and roughly 150 m across, which makes a full crossing about 300 m return — a proper swim. In July the surface reaches 20 °C but the spring-fed layers below stay at 15 °C, so it cools noticeably once you leave the top metre.

Getting out

Climb out at the same jetty. The ladder is wooden and can be slick with algae by late summer; grip the handrail, not the rungs.

Hot showers are inside and included. This is genuinely unusual for an outdoor bathing spot in the UK and is the reason the pond stays busy in February.

Depth profile

A natural clay-lined pond, not a pool: the bottom is silty in the corners and firm in the middle, sloping from 0.8 m at the two entry jetties to about 3 m in the centre. Because it is spring-fed the water is a consistent 5 °C in winter and 20 °C at the surface in July — a wider annual swing than any heated lido.

Season window

Year round; lifeguarded daily 07:00–20:00 in summer, 07:00–15:00 in winter

Cold-water questions

Is the Hampstead Mixed Pond heated?

No. It is spring-fed and unheated, running from about 5 °C in January to 20 °C in July, which is a wider annual range than any heated lido on this list.

Do you have to book to swim at the Mixed Pond?

No booking, but a ticket is required and there are session closures on Christmas Day and during the winter pond maintenance in early January.