Conversation so far:
When was the first circumnavigation?
In 1679, Dampier joined the crew of the buccaneer Captain Bartholomew Sharp on the Spanish Main of Central America.
What was his position?
CANNOTANSWER.
What happened during the trip?
took part in the capture of Spanish ships on the Pacific coast of that isthmus.

Question: Why did they circumnavigate?
Self-contained rewrite: Why did the crew of buccaneer Captain Bartholomew Sharp first circumnavigate?