It will cost you many a clam to go on a Mongolia Fly Fishing Float Trip as advertised at fishmongolia.co.uk. Whether it includes shelter—or what sort of shelter it might entail—is unclear, but for Chris Santella the price and risks that go with such a trip are worth the adventure. For his first book, Fifty Places to Fly Fish Before You Die, Santella polled “master fly fishers about some of their favorite fly-fishing experiences” and came up with a list of sites—including exotic islands, imposing North American locales, and various nether regions—that are as picturesque as they are expensive. Each spot profiled comes complete with an essay and an “If You Go” section that includes an overview of when to hit a particular area and what sort of equipment to bring if you do. For the record, Santella’s full Mongolia trip includes “riverside accommodations” and starts at $5,200—“mare’s milk vodka… optional.” Santella discusses his work at 7 p.m. at Olsson’s Books & Records, 2111 Wilson Blvd., Arlington. Free. (703) 525-4227. (Mike Kanin)