The ferry fare is US$7 or BZ$14. You can buy the pass, a blue casino chip, at the ferry office which is on the jetty. Or you can pay the on ferry. They even have a portable credit card machine on the bigger boats so you can pay by credit card. If there is four or more in the party you could well find it cheaper to use a water taxi. We used Armando Gonzalez. His contact details are 00 501 610 1448, and his e-mail address is armandogonzalez708@yahoo.com. If you’re booking him, make sure you get a reply to confirm he’s coming. His fee from San Pedro to Journey's End (4 miles) was US$20. The other advantage of water taxis is their flexibility of time, as the Island Ferry runs only every two hours. The transit time with the Island Ferry depends on just how many stops it make en route. For us the quickest between Journey's End to San Pedro was nine minutes (non stop) and the longest was 40 minutes calling at nearly every jetty.
If your resort is good then it is unlikely you will need a weekly pass for the ferry to visit San Pedro daily.
Most of the scuba dive schools are based in San Pedro and if you plan to go diving, then the majority of dive schools will actually collect you and deliver you back home for free.
You should check to see if your resort has bicycles. If they have then cycling along the beach to and from San Pedro can be good fun, especially as there are numerous places to stop for refreshments. But do beware that the prevailing wind is from the north so cycling back can be slower than the south bound leg.
Have fun.