Mainstream cruise lines, even those that attract an older and more luxury-minded clientele, are generally open to all age groups. If you are hoping for a true adults-only cruise, check out one of these ships that restricts guests to 18 and over cruisers only.

Viking Ocean Cruises

Viking River Cruises started the new Viking Ocean Cruises, which offers a completely different experience than other well-known cruise lines. You won’t find casinos here, art auctions, additional-fee alternative restaurants, spa entrance fees or additional charges for Wi-Fi, nor will you find anyone under 18. All staterooms have a veranda and luxurious amenities like a duvet and goose-down pillows. Choose from eight on-board dining options, all of which are available with no additional charges or fees.

Itineraries for Viking Ocean Cruises span the globe, with ones available that include Africa, the Baltic and Scandinavia, Asia and Australia, the Mediterranean and the Caribbean. Sailings include one free shore excursion in every port.

Saga Cruises

You must be at least 50 years of age to book one of the small-ship cruises from Saga Cruises. Itineraries include everything from the Mediterranean to the northern lights. Saga offers a lot for your cruise fare with the “everything is included” design. This includes chauffeur service to your U.K. port and all your service charges and gratuities.

P&O Cruises

P&O Cruises is another British line that offers a mix of family-friendly ships as well as several reserved exclusively for adults. Arcadia and Oriana are mid-sized adults-only ships and Aurora will be adults-only starting in April 2019. Expect itinerary options that range from three-day Guernsey cruises to much lengthier excursions, including a 29-night cruise from Singapore to Southampton on Arcadia.

U by Uniworld Cruises

U fleet launched in 2018 by Uniworld River Cruises and is only open to cruisers at least 18 years of age. The two ships, The A and The B, have programs designed to appeal to younger adult cruisers, including rooftop venues, international DJs, communal tables, gym equipment and more. Hang at the Ice Bar, which can be lowered with hydraulics to fit under passing bridges. Excursions favor active travelers as well and include sports like kayaking. The U by Uniworld matte-black ships are stylish and designed to be part boutique hotel, part yacht and part local hotspot.

U by Uniworld offers shorter itineraries of eight days or fewer, and the trips are less inclusive when compared to regular Uniworld cruises. Accommodations range from economical studios, including a triple studio cabin with three twin mattresses, to luxury suites with French doors and balconies.

Virgin Voyages

Starting in 2020, there will be another option for adults-only cruises when Virgin Voyages takes to the seas. Cruisers will get benefits like unlimited Wi-Fi, complimentary dining, basic beverages, entertainment and more. RockStar Suites will have extra benefits including complimentary local transportation, fully-stocked in-room bar and even luggage assistance from a wardrobe team who will unpack and repack all your belongings.

These ships will even have a dedicated topless area where you can work on your tan, sans the tan lines. Onboard gratuities are covered and the dress code is far less strict than other ships. You won’t find a big-cruise-ship-style buffet either. The Galley will feature a market of food-truck inspired vendors, complete with sustainable packaging, and you can order room service or dine in one of the ship’s restaurants.