His amputations were required due to a severe electric shock accident which occurred in March 1994. At the time, Croizon was employed as a steelworker at the foundry of Poitou, 26 years old and married, with one son; his wife was expecting a second child. At his home in Saint-Rémy-sur-Creuse, Vienne, while standing on a metal ladder on the roof to work on a television antenna, Croizon received a severe electric shock from a high-voltage power line which earthed through the ladder, to which he became adhered. Twenty minutes passed before a neighbour could raise the alarm. He was hospitalized in Tours, where doctors removed his left arm above the elbow, his right arm below the elbow, then his right leg above the knee. Surgeons had thought that the left leg could be saved, but when that also required removal, Croizon reported feeling "despair".
English Channel Challenge
Preparations
During his recuperation in the hospital, he saw a television programme about a female channel-swimmer, who Croizon said inspired him. He began a regimen of swimming, training for over five hours per day with the Maritime Gendarmerie, the French marine police, in the sea near La Rochelle. He experimented with different prosthetic limbs designed for swimming, with fins attached to the stumps of his legs. One set of specially designed prosthetics cost €12,000, and are made from carbon and titanium. He wrote a book entitled J'ai décidé de vivre, using a speech-to-text computer system. He also made a parachute jump. Croizon's preparations for the channel-swim attempt took 35 hours per week for two years; throughout the training period, he received letters of support from national politicians, including then-President of France Nicolas Sarkozy. It was during this period that he completed a swim from Noirmoutier to Pornic in less than five hours.
Event
On Saturday, 18 September 2010, at the age of 42, he swam across the English Channel in less than 14 hours. He set off from Folkestone at 06:45, arriving at Cap Gris Nez at 20:13, a distance of. After the crossing, he reported that he had felt pain, but was confident that he would finish.
Intercontinental Straits Swimming Challenge
In April 2012, Croizon announced a new project, to swim four straits separating five continents, in which he would be accompanied by long-distance swimmer Arnaud Chassery. The planned trips included Australia to Asia, across the Red Sea, the Straits of Gibraltar, and the Bering Strait. Croizon completed the first swim, linking Australia and Asia, in May 2012, when he swam from Papua New Guinea to Indonesia in seven-and-a-half hours, accompanied by Chassery and a local man, Papua New Guinean Zet Tampa, who swam with them in support. Their course was along New Guinea Island, shared by both countries. In June, he crossed the Red Sea from Egypt to Jordan, over a distance of in about 5 hours. Croizon completed his Straits of Gibraltar crossing in July, from Tarifa, Spain, over 14 km, to land near the city of Tangier, Morocco. He completed the journey with a friend in "just over five hours." His planned August Bering Strait swim from Little Diomede Island, across the international date line, to Russian Big Diomede, was to occur a week after the 25th anniversary of Lynne Cox's historic crossing on 7 August 1987. Croizon's training regimens included temperature conditioning for the below 40-degree water by swimming in ice-melt mountain lake water, and ice water baths. The August 13 dawn attempt was delayed, then canceled, due a storm arriving early. When a lull in the bad weather arrived on 17 August, the team's start was delayed by high waves until the late afternoon. Croizon and Arnaud completed the 4.3 km swim across the Bering Strait in one hour and 20 minutes. Dense fog and strong currents added time and distance to the trip in 4 degree C water. After crossing the International date line, they continued for a few hundred yards to Great Diomede island in Russian waters without official permission.
Wheelchair
Croizon has a customised electric wheelchair that cost €24,000 to build. In August 2013 it was stolen, but recovered a few days later after much publicity in the media and on Twitter.