Eryri, also known as Snowdonia, is a breathtaking landscape which is not so far from the big cities that its remoteness can be underestimated. When a Londoner uses his day off to take a spontaneous hike up a mountain with no map and no plan, panic sets in when he finds himself lost and with no phone signal to raise the alarm.

In southern Eryri, a walker slips near a waterfall on a freezing winter’s afternoon. As darkness falls, he’s miles from help – so the teams can waste no time reaching him and carrying him by stretcher across the fields to safety.

A holidaymaker from Birmingham decides to take one final trip of the day in his dinghy at Barmouth beach. But when the motor fails and the starter pull-cord snaps, he finds himself drifting out to sea with no mobile phone, no warm clothes and no food or water. Soon, darkness falls. It’s pitch black, and the RNLI and coastguard rescue teams are finding it difficult to locate him - until a member of the public watching from the shoreline comes up with an unexpected way they can help.