Calling all marathon swimmers...this is the one you have been waiting for! This is our longest sea swim yet, taking place in the wild Atlantic waters of Killary Fjord.

Entry requirements:

• Ages 18+

• Proof of completing a 3.9km race in the past year in under 1:45 hours

• Skins swimmers must show proof of swimming at least 3.9km in similar conditions

Because the fjord is fed by several rivers, heavy rainfall may drop water temperatures below normal (<12  degrees). All swimmers will receive a GPS tracker for safety.

Cut-off times: Reach 4km in 2 hours and finish within 4 hours total