If you booked the 10:30 dolphin swim at Blue Lagoon, you should still be OK... because the Disney dolphin encounter there is also the 10:30 start time. It's apparently a 15-minute trip from the cruise terminal to the ferry to Blue Lagoon, which you have to be at by 10:00 to catch the ferry. So as long as you get off the ship as early as possible, you should be OK. (I have the exact same issue, btw, and both the dolphin people and the
travel agency that booked my swim said that we shouldn't have any problems unless we're late getting off the ship).
HTH!