Tourists look at Margerie Glacier on the cruise ship

FON THACHAKUL/GETTY IMAGES

It’s not too late to book a once-in-a-lifetime summertime excursion.

Alaska is hot: It’s No. 2 after Hawaii on boomer bucket lists for domestic travel, according to a 2017 AARP survey, and more than 1 million passengers are expected to sail its waters in 2018. Summer is the peak time for an Alaska cruise, and it’s not too late to book for the 2018 season. Just move fast. Some of the best Alaska cruises sell out months in advance.

June, July and August are also the most expensive months to cruise, so you’ll find bigger savings and better booking options if you choose a shoulder-season excursion in May or September. The amount varies by cruise line (some offer no price break at all), but deal hunters can find savings of 20 to 35 percent. The downside? The weather is less predictable and animals are less active.

Some cruises to consider:

Big: ‘Norwegian Bliss’

The cruise biz is buzzing about Alaska’s newest and largest cruise ship, which will debut in June. The Norwegian Bliss holds 4,004 passengers and 1,716 crew members, and features some grandkid-friendly firsts for an Alaska cruise— including an open-air laser tag course and the largest go-kart track at sea. Adults can check out the Cavern Club, modeled after the legendary Liverpool hot spot and featuring a Beatles cover band. If you’re more intrigued by the scenery, the ship offers a 20,000-square-foot observation lounge.

Cost: The lowest prices are $969 per person for an inside room (an ocean view starts at $1,479; a balcony at $1,599) for a seven-night cruise departing on June 2, for example. It departs from Seattle, and stops include Juneau, Skagway and the Sawyer Glacier. On any cruise, prepare for hidden charges: Taxes, fees, and port expenses can cost from $150 to $250 per person.

Midsize: Royal Caribbean International’s ‘Radiance of the Seas’

Big views are plentiful on this 2,466-passenger ship, which features floor-to-ceiling windows, glass elevators and a nine-story glass-enclosed atrium. “You always have a front-row seat to the Alaskan wilderness on this ship,” says Don Bucolo, editor in chief of EatSleepCruise.com. Radiance of the Seas was refurbished in 2016 and boasts an outdoor movie screen and a rock-climbing wall. Travelers can choose a northbound or southbound route, departing from Seward or Vancouver. The ship passes through the Inside Passage (a habitat area for wildlife such as eagles, sea lions and whales) and along the 76-mile-long Hubbard Glacier.

Cost: The cheapest fare for a four-night cruise starts at $499 per person for an interior cabin (an outside view is $599; the balcony is $799). It leaves from Vancouver on Sept. 6. The lowest fare for a seven-day cruise — departing from Vancouver on May 18 — is $679 for an interior cabin ($962 for an outside view; $999 for a balcony).

Midsize: ‘Coral Princess’

This 2,000-passenger ship won eight prizes in CruiseCritic.com’s 2018 Cruiser’s Choice Awards, including best shore excursions, best value, and best overall cruise for the midsize category. The shore excursions include not only the usual wildlife tours, but cultural activities — such as watching a lumberjack competition — and fishing trips. The seven-day cruises depart from Anchorage and Vancouver. Another good midsized option: the Holland America Westerdam, a 1,916-passenger ship that won three prizes in the Cruiser’s Choice Awards. Holland America’s modern, midsized ships evoke the golden age of ocean liners, says Anne Vipond, author of Alaska by Cruise Ship, with nostalgic touches such as teak promenade decks lined with steamer chairs.

Cost: The best prices are in May: A seven-day cruise on the Coral Princess departing from Anchorage on May 16 starts at $448 per person for an interior room ($558 for an ocean view; $998 for a balcony). How much do prices rise in summer? For a cruise departing July 18, an interior room starts at $1,059 per person.

Cruise ship near the Hubbard Glacier

MALORNY/GETTY IMAGES

One of the more popular summertime getaways, more than one million visitors will enjoy an Alaskan cruise this summer — stops include Anchorage and Vancouver.

Small: ‘National Geographic Quest’

If you want to try an expedition cruise, the National Geographic Quest is a good place to start, says Colleen McDaniel, senior executive editor of CruiseCritic.com. Expedition cruising involves higher prices and smaller boats — the Quest holds 100 passengers — and focuses more on biology lectures than Broadway shows. As you might expect from National Geographic, the ship includes a photo instructor, an undersea specialist, and facilities for presentations (it also has an onboard spa and gym, which is unusual for small expedition ships). A sister ship, the Venture, will debut this summer. If you want something smaller, try the company’s recently refurbished 62-passenger Sea Lion, which gets good ratings from cruisers, says McDaniel.

Cost: Because they hold a tiny number of passenger and provide more intimate experiences, expedition cruises can be pricey. A 14-day cruise on the Quest, which departs from Seattle and Sitka, starts at $9,990 per person. If you want something less expensive, National Geographic has a six-day excursion that starts at $4,290 and departs from Sitka and Juneau.

Really small: UnCruise Adventures’ ‘Safari Quest’

The Safari Quest is a 120-foot-long yacht, carrying 22 passengers and 10 crew members. That small size offers big advantages for photographers and nature buffs, since it’s nimble enough to pull close to waterfalls and bears, and it reaches nooks that UnCruise’s other ships can’t. (The Endeavor, the largest of the company’s four vessels, holds 84 passengers.) If you’re feeling ambitious, you can take a polar-bear plunge from the ship into the chilly waters of Alaska. Also check out Alaskan Dream Cruises: Its five ships include the 60-foot-long Misty Fjord, which carries 10 passengers and was designed for up close wilderness exploration.

Cost: An eight-night trip on the upscale Quest (round-trip from Petersburg) starts at $7,495 per person. The boats embark from Seattle, Juneau, Sitka and Ketchikan. UnCruise’s lowest-priced trip starts at $2,945 for seven nights from Juneau to Ketchikan (or reverse).

Before you book an Alaska cruise

Choose the correct side of the ship

If you’re taking a one-way cruise between Vancouver and Seward or Whittier, you’ll get the best views of mainland mountains from a starboard cabin when you’re heading northbound, says Vipond. If you’re heading southbound, get a port cabin. The side of the ship isn’t critical for a round-trip cruise from Vancouver or Seattle, she says.

Splurge on a balcony

“You’ll kick yourself if you book an inside cabin instead of a balcony stateroom,” says J.D. Lasica, founder of Cruiseable.com. “There’s great scenery along the Inside Passage and chances are you’ll spot some wildlife.”

Consider a specialist

Cruise planning can be complicated, especially for first-time travelers. The Cruise Lines International Association (CLIA) offers a searchable database of certified cruise travel agents that can help you plan your trip. Among the upsides: Most specialists take courses on the cruise biz, they can find deals, they’ve been onboard the ships, and — best of all — they don’t charge a fee.