Thomas and the Dorchester crew were at Cape Ann in 16241 for the purpose of establishing a colony. Other than commerce, there were several reasons for leaving England.2 After the 1492 voyage of Columbus, exploration of the east coast had continued without stop. English ships traveled up and down the coast, mapped the area, looked for spots to fish or to settle. John Cabot's3 explorations for the English is an example. Cape Cod was visited and named as early as 1606 because of the plentiful fish found in the region. Settlement attempts were made at several points, from Maine (Popham Colony) down, with Virginia being a well-known survivor. Jamestown was founded in 1607. While Newfoundland found success very early, in 1588, there were other attempts. The effort at Roanoke Colony (North Carolina) ended in tragedy in the 1580s.    

Footnotes: 
1. See Cape Ann retrospective
2. See Plus or minus the arrival
3. See Gardner's Beacon, Vol. III, No. 1
Thomas Gardner was an Overseer of the "old planters" party of the Dorchester Company that landed, in 1624 at Cape Ann, to form a colony. The party landed at, what is now known as, Gloucester. Thomas is considered by some as the 1st Governor of Massachusetts,1 due to his being in authority in the first settlement that became the Massachusetts Bay Colony (which later subsumed the Plymouth Colony). Thomas, and his wife, Margaret Fryer,2,3 had nine children and many descendants.

Footnotes:
1. See thomasgardnerofsalem.blogspot.com/2014/07/1st-governor.html
2. See thomasgardnerofsalem.blogspot.com/2012/11/how-many-wives.html
3. See Research Project (Sherborne,Dorset)