Charter boat vs. Sea Lanes
The rulebook (Page 6) is actually quite clear on this:

SEA LANES &amp; SEA ROUTES
Locations are connected to each other in the ocean by sea lanes.
Locations directly connected by a sea lane are adjacent.
A series of connected sea lanes is called a sea route.

Given this definition of a sea route, you can only charter a boat from and to a location where you can trace a continuous series of series of sea lanes. So your option 1 is the correct interpretation.