After finishing his high school education, he travelled to Uganda as a volunteer in a gap year teaching scheme organised by Africa & Asia Venture.
[citation needed] In May and June 2006, Cornthwaite skateboarded along Britain's End-to-end route from John O' Groats to Lands End, a distance of 1,442 kilometres (896 mi).
[2] From 3 to 16 April 2011, Cornthwaite and Sebastian Terry journeyed 1,400 miles (2,300 km) from Vancouver, British Columbia, Canada, to Las Vegas by tandem bicycle.
[7][8] On 19 June 2011, Cornthwaite began a 2,340-mile (3,770 km), Guinness World Record-setting journey down the Mississippi River from source to sea on a stand up paddleboard.
Hurricane Lee caused Cornthwaite to leave the water for a time, lengthening the trip to a total of 82 days.
[9] In March 2012, in a fifth adventure for Expedition1000, Cornthwaite and a crew of ten sailed from Cabo San Lucas, Mexico, to Honolulu, Hawaii.
During this time, Cornthwaite and Emily Penn (the program director of Pangaea Explorations) conducted a series of workshops on topics ranging from ocean science to social media to diagnosis of personal happiness and purpose.
[12] In June 2010, Cornthwaite and Sarah Outen paddled 150 miles (240 km) from Bath to beneath the Tower Bridge in London.