With striking glaciers, craggy peaks and steamy geysers, Iceland appeals to the curious and the adventurous. In recent years, this remote and cold island-nation has vaulted from out-of-the-way backwater to can’t-miss destination. Tourism is booming.

Part of the recent travel surge is convenience, of a sort. Nowadays, many Americans are dropping in to Iceland on their way to or from Europe. Both Icelandair and Wow Air typically allow a 24-hour or longer stopover for no additional airfare: All you need is a passport, a rental car and an extra day or two.

The challenge for the casual visitor is figuring out what to cram into a 24-hour stay. Iceland is famously spectacular, but you’ll have a spectacular time only by making a good plan in advance.

If you thrill to the idea of an Iceland stopover, consider the whirlwind itinerary outlined here. These suggestions assume you’ll visit in summer, when the roads are clear and daylight is virtually endless. From early June to mid-July, it never really gets dark, letting you extend your daylight sightseeing day as far as your energy level will take you.

The capital city, Reykjavik, is the natural hub for any visit, with an excellent assortment of accommodations, restaurants, shops and nightlife. Reykjavik easily has enough sights to fill a day or two, but with limited time, I’d spend most of my daylight hours out in Iceland’s legendary countryside.

Morning: Most U.S. flights to Iceland land in the early morning hours at Keflavik International Airport. Conveniently, the famous Blue Lagoon thermal-bath spa is just 20 minutes from the airport — and in the summer it opens at 7 a.m. By the time you deplane, clear customs and pick up a rental car, you can head straight there for a relaxing outdoor soak in milky blue geothermal waters. But you can’t just show up and hope to slip in — reservations are required; to have your choice of time slots, book at least several days ahead (www.bluelagoon.com).

Midday: Refreshed from your soak, drive 50 minutes into Reykjavik. Check into your hotel, have lunch and browse a bit. I’d walk down to the harborfront for a photo op at the popular Sun Voyager sculpture (shaped like an old Viking boat), then follow the shoreline past the cutting-edge Harpa concert hall and moored boats to the Old Harbor, where you’ll find a few seafood restaurants on the piers.

Afternoon: Set out from Reykjavik to the Golden Circle route for some serious sightseeing. This excursion offers a rewarding ratio of natural wonders per miles driven. Without stops, the entire circuit requires about four hours of driving — but a long Icelandic day will let you wring the maximum out of your visit.

The essential trio of stops along the way includes Thingvellir National Park, situated in an extraordinary gorge caused by the slow separation of the Eurasian and North American tectonic plates; a bubbling, steaming geothermal field with Iceland’s most active geyser — Geysir; and Gullfoss, one of the country’s most impressive waterfalls. Since these major Golden Circle sights technically never “close,” you can go at your own pace without eyeing the clock.

Evening: Grab a bite to eat in Golden Circle country (limited options) or hold out for your return to downtown Reykjavik. Restaurants in the city keep long hours; you’ll find plenty of spots still serving as late as 10 p.m. Food and drink are expensive in Iceland — but at least you’ll pay exactly what you see on the menu (there’s no tipping, and taxes are included in the menu prices). You can always economize by eating an Icelandic hot dog (pylsa), a fast-food favorite made from Icelandic lamb, pork and beef.

Late: Collapse at your hotel and sleep for a few hours. Drop your car at the airport and fly out the next morning.

For a longer layover: With 48 hours, add a visit to the dramatic South Coast, which sits in the shadow of two glacier-topped volcanoes. With remarkable waterfalls (Seljalandsfoss), black-sand beaches (Reynisfjara) and hikable glaciers (Solheimajokull), the South Coast is a close runner-up to the Golden Circle as a top day trip. Plan on a 21/2-hour drive each way (without stops), or consider joining a bus excursion from Reykjavik.

Packing tips: Even in summer, prepare to bundle up. Cool temperatures and bone-chilling wind can happen at any time of year. Remember your swimsuit for visiting a thermal bath, and bring sunglasses for driving with the sun low in the sky.

With its stunning natural wonders, kind and gregarious people, and unique attractions, this little island stubbornly exceeds the lofty expectations of its many visitors. Whether or not you can pronounce the names on its map, Iceland is a rewarding place to travel — even in just one jam-packed day.

Rick Steves (www.rick steves.com) writes European travel guidebooks and hosts travel shows on public television and public radio. Email him at rick@ ricksteves.com and follow his blog on Facebook.