The astronomical first day of summer will see the sun rise at 4.37am and set at 9.28pm, bringing the day's length to 16 hours, 50 minutes and 43 seconds. This is nine hours and 12 minutes longer than the winter solstice on December 21.
June solstice in Peterborough is at precisely 4.32am - just after the sunrise session begins at Peterborough Lido.
Doors open for the morning swim at 4.30am and the session will last until 7.30am. The cafe will be open offering breakfast.
The late night moonlight session, from 7pm until 10pm, is sold out.
Peterborough Lido was recently listed first in National Geographic magazine's rankings of the 10 best lidos in the UK - so what better place to watch the sun rise on the longest day of the year?