Anyone can use the Friendship boats between Epcot and DHS. So, if you're having a meal or otherwise visiting Swalphin, it is fine to get on the boat to DHS. I think it's about a 10 minute ride from Swalphin to DHS (that doesn't account for the waiting time). They say it is about 30 minutes from Epcot to DHS (and the reverse). There are stops at BW, BC/YC, and Swan-Dolphin. It's a pleasant way to get to the parks.