You’re wasting away all right. But instead of Margaritaville, you’re on some South End roof deck waiting for another round of watery mai tais.

Hang on one more day, then you can do some actual island hopping in Boston Harbor. That’s right, land shark, tomorrow The Island Alliance, together with the Institute of Contemporary Art, opens its four-island installation, Art on the Harbor Islands.

Jump on the Spectacle Island Ferry at Long Wharf to walk through “Core Sample,” an interactive audio piece. A trip to Georges Island takes you to “Voromuro,” a sculptural installation, or to join artist Ernesto Pujol as he leads a silent performance walk (four walks are scheduled across the islands). Another ferry over to Lovells, and you’ve got “Waterside,” a series of models and drawings enclosed in a yurt.

Visit two in a day or take your time and spread them out over the summer.

It beats searching for your lost shaker of salt.

Through October 8. Ferry tickets ($7-$12) cover round-trip and all interisland transportation. For ferry information and schedule, go to bostonislands.org. Institute of Contemporary Art, 100 Northern Avenue, South Boston (617-478-3100 or icaboston.org).

Photo credit: Blaine Anderson and Ernesto Pujol, 2007.