The celebrities face their fears for the first time with a punishing 500m swim in Lake Windermere. Georgia struggles with her anxiety, and Alex fears a Channel swim could be a challenge too far.
The celebrities face their first open water experience. Arg goes on a diet, Alex struggles with a shoulder injury, and an ambulance is called for Tessa after a brutal sea swim.
The celebrities tackle their first ever night swim in the freezing waters of Loch Lomond, and decide which of them really has it in them to attempt the impending Channel crossing.
The Channel swim is fast approaching and the experts must decide whether the remaining celebrities have it in them to take on the ultimate swim test - crossing the channel in relay.