A Somali police officer arrests a suspected rebel member of the al Qaeda-affiliated al Shabaab among beach goers in Mogadishu. Al Shabaab claimed responsibility for today's pre-dawn attack on a Kenyan university campus near the Somali border. The following gallery examines who is al Shabaab. Here: Somali police officer (R) arrests a suspected rebel member (L) of the Al Qaeda-affiliated al Shabaab among beach goers at the Lido beach north of Somalia's capital Mogadishu March 23, 2012. (Photo by Feisal Omar/Reuters)

A surfer runs down the beach past hundreds of Barbie dolls comprising the sculpture 'Wave 2' by West Australian artist Annette Thas on Tamarama Beach during the 19th annual Sculptures by the Sea exhibition in Sydney, October 23, 2015. Sydney's coastal walk between Bondi and Tamarama has been transformed into a temporary sculpture park featuring over 100 sculptures from Australian and international artists, billed as the largest free sculpture exhibition in the world. (Photo by Jason Reed/Reuters)

Yanelis Blanco, 24, center, dances with a group of friends at Santa Maria beach, about 15 miles from Havana. It is the closest beach to Havana. Others, from left to right are Jackson Miranda, 21, Dayan Suarez, 24, and Melisa Oliva, 15. The men in the group have a rap group together. The government is demolishing buildings all over the coast of East Havana and recovering and restoring beach dunes. (Photo by Sarah L. Voisin/The Washington Post)

Members of the Coney Island Polar Bear Club warm up before swimming at the beach at Coney Island in New York, December 15, 2013. (Photo by Eric Thayer/Reuters)

A general view of Copacabana beach during the coronavirus disease (COVID-19) outbreak in Rio de Janeiro, Brazil, March 22, 2020. (Photo by Ricardo Moraes/Reuters)

People collect fish on the beach during the coronavirus disease (COVID-19) outbreak in Da Nang, Vietnam on May 6, 2020. (Photo by Kham via Reuters)

A Palestinian man demonstrates his parkour skills on a beach as the coronavirus disease (COVID-19) restrictions ease in Gaza City on July 10, 2020. (Photo by Mohammed Salem/Reuters)

Members of the public take to the water at Barassie Beach in Troon, on the west coast of Scotland on Boxing Day, December 26, 2020 as Storm Bella brings rain and high winds to the UK. (Photo by Andy Buchanan/AFP Photo)