The man known for circumnavigating the globe was Magellan. Not very many people survived this voyage. Only 18 men and one ship, the Vittoria, survived. Magellan died in the Philippines. http://www.thenagain.info/webchron/westeurope/magellan.html
de Gama saild around the Cape of Good Hope. This is the southern part of Africa. After he did this he was the first to go to India from sailing around Africa. http://library.thinkquest.org/4034/dagama.html
Zheng He was a Chinese sailor. He went around telling everyone how powerful China was and trading. When he died the emperor stoped ship making and had some of his ships destroyed. http://www.chinavoc.com/history/ming/zh.htm
The Vikings were the first people to discover Greenland. They were on iceland and sailed west. They eventually landed in Greenland and named it that. http://www.eyewitnesstohistory.com/vikings.htm