Sebastian Cabot almost certainly travelled with his father, John Cabot who was serving the English Henry VII in his attempts to find a Westerly route to Asia. He was fortunate not to travel with his father's expedition that disappeared in 1497/8. He was able to put together an expedition to continue his father's work to discover the North West passage and crossed back to the New World to seek routes to China. It is feasible that he discovered Hudson's Bay but the icebergs and weather intimidated his crew who wished to return to England.
The young Henry VIII continued to employ Sebastian as a cartographer to update the Crown's collection of maps. Henry was interested to learn of the extent of new Spanish empire and in 1516 despatched Sebastian Cabot with Sir Thomas Pert to explore the islands of the Caribbean and the coastline of Brazil. The voyage came to an abrupt end once the Spanish made it clear that they did not welcome prying eyes. In Hispaniola the two ships of the expedition came under fire and Pert ordered a withdrawal back to England. Sebastian was somewhat disappointed by this turn of affairs and realised that the best way he could continue his exploratory endeavours was to work with the Spanish rather than against them. He spent the next three decades working for the Spanish Crown. During this time, he was able to map and discover much of South America.
He did return to the employ of England in 1547 to work for the young Edward VI. The English Crown was delighted to have so much insider knowledge of the Spanish Empire become available to them. Sebastian was given the title 'Great Navigator' as he helped update the maps and knowledge of the English. He became an advisor to various expeditions looking for the North-East passage (via Russia) and became a life time director of the Company of Merchant Adventurers who underwrote much of these attempts.