Cancer charity Macmillan have added a new lido to their roster of outdoor pools for the All Out Swim challenge. Swimmers can take on a 2k or 5k challenge at Parliament Hill lido in Hampstead on 29 September. The outdoor swim series also takes place at Letchworth, Pells Pool, Guildford and Sandford Parks Lido in Cheltenham in September and October. See macmillan.org.uk/alloutswim for more details.