The Seaburn Boxing Day dip started in 1974 and claims to be the biggest of its kind in the northern hemisphere, attracting 1,000 swimmers in fancy dress, cheered on by over 5,000 supporters. Swimmers are doused by the fire brigade before jumping into the North Sea. “It’s mass hysteria that takes them in and hypothermia that brings them out,” says Stuart Kohn, from Sunderland Lions Club. This is a charity fundraiser, and you can enter as an individual or a team. Minimum age 12 years.
Further information and registration: https://e-clubhouse.org/sites/sunderland_uk/page-6.php
This is a crowd-sourced map. Abilities vary, and conditions change. Always assess risks for yourself before getting in.
Be careful of the North Sea tides and currents. The site is popular with surfers, windsurfers, kite surfers, and sometimes jetskis, so swim in groups and wear brightly coloured hats. There are rocks which are submerged at high tide.