Karen Jettmar, author of The Alaska River Guide, the standard guidebook on floating Alaska's rivers, leads challenging rafting, sea-kayaking, and hiking trips and base-camp wildlife viewing each summer in some of the wildest and most exotic places around the state. Her groups are tiny, with five to eight members, and she offers custom coed, family, and women's trips. After 2 decades leading and teaching clients, Jettmar's firm was recently recognized as one of the world's best by National Geographic Adventure. A 10-day Arctic float trip costs around $4,200.