Outfitters keep coming up with creative methods to entertain (and scare the crap out of) us. Follow South Africa's famous sardine run—a migration that draws dolphins, game fish, seals and great white sharks—aboard a 70-foot long-range fishing boat with local outfitter Extraordinary Expeditions. Guides zoom out to the action, then you jump off into the melee with scuba gear. $5,200; six-night trips in May and June; unchartedoutposts.com. Abercrombie & Kent's trips are normally cushy, but this year it introduced 15 new Extreme Adventures. Our pick is the seven-day Trails of the Iditarod trip, in Alaska. Meet four-time Iditarod champion Martin Buser, learn to mush, and build your own snow cave to sleep in. $9,225; April 2–8; akextremeadventures.com. Walk across Iceland—all of it—on a 31-day traverse with Icelandic Mountain Guides. Backpackers go from north to south through a stark landscape peppered with monster waterfalls, active volcanoes, and blue glaciers. $3,900; June 26–July 26; ountainguides.is.