If you count all its islands, Alaska has almost 34,000 miles of shoreline—far more than any other state. Jumping on a day cruise gives you unparalleled views of those dramatic, steep-walled fjords and sloping beaches of sand or shale, where bears forage for seafood and tidewater glaciers spill house-sized chunks of ice into the sea.

Taking to the water also opens up a fascinating new window into Alaska's wildlife. Cruising is the best way to see aquatic animals like humpback whales, orcas, massive Steller sea lions and sea otters. You'll also get a new perspective on Alaska's magnificent seabird colonies, which make their homes on sheer cliffs that are inaccessible by any other means. Sometimes you'll also see bears, mountain goats and even deer along the shore.

Almost all day cruises have warm, indoor accommodations you can retreat to if things get chilly or wet. But bad weather can mean good things: Believe it or not, a gray, drizzly day often makes for great whale-watching, because the cool temperatures and limited sun bring their food closer to the surface.

Ocean-going day cruises are available in most parts of the state, but they're especially popular in Kenai Fjords National Park, Prince William Sound, Glacier Bay National Park and all the way up and down the Inside Passage.

If you're traveling through an inland portion of the state, look for river cruises, where you can ride in a jet boat as it races up mighty glacier-fed rivers, or tour through iconic Alaskana sights—including a simulated Alaska Native village and watching a bush plane take off—in an authentic stern-wheel paddle boat.