The ORCA card is all you need to pay your fare on Sound Transit, Community Transit, Everett Transit, King County Metro, Kitsap Transit, Pierce Transit, Seattle Street Car, Seattle Monorail, the King County Water Taxi, and Washington State Ferries.
Transferring is easy with an ORCA card. When you use the ORCA card to transfer between ORCA-family transit services, your first-leg fare counts toward to the second leg of your trip. If the second leg of your trip costs the same or less than your first, your transfer is free. If your second-leg fare costs more than your first, your ORCA Card will automatically deduct the difference from your E-purse balance. Transfer values expire two hours after you first tap your ORCA Card to begin your trip.