EIL MALK, PALAU: Islands are wilder and weirder than continents. They're harder to get to, harder to spoil. Count me in. My best natural experiences take place on islands. And for me the challenge of getting there heightens the experience. True, I complain as loudly as anyone about security lines, tiny middle seats and overnight flights. But when I slip into Dominica's cool waters on the way to an underwater volcano or compete with grizzlies for salmon amid the evergreens of British Columbia, the thrill is doubled because I've earned it. Some of these five outdoor adventures can be reached in hours; some take days. All of them, for me, were eye-opening and jaw-dropping. And none more so than snorkeling in Jellyfish Lake on Palau's Eil Malk Island.