Virgin Voyages is the 'cool mom' of cruise lines — and it's only for adults. Here's what to know before booking so you're not disappointed.

Virgin Voyages has a "come as you are" attitude, which translates to no rigid rules like set dining times or formal nights.

Unlike other cruises, its ships don't have one main dining room with strict meal times. You pick a restaurant and eat at it (but those who do crave structure can make reservations).

With Virgin Voyages, you're not required to dress up for formal evenings or wear nice slacks to dinner.

Travelers can dress how they please, from swimsuits to smart casual to glam. The only requirement is to wear something.

Although, passengers can sunbathe topless on the sun deck.

Common things you find on cruises won't be found on Virgin Voyages. This includes:

• Children — All Virgin Voyages cruises are 18 and older.

• Buffets — Instead, the ships have food halls and multiple restaurants.

• Onboard photographers — If you want photos, bring a selfie stick or ask a fellow traveler.

• "Port" or "starboard" labels — The ship uses "A" and "Z" instead.

• Self-service laundry — Your laundry can be done for you for a fee, though.

• Towel animals — You won't find these cruise staples on your bed at night on a Virgin cruise. Turndown service is only available by request.

Although many cruises will have travelers board pretty early, boarding doesn't begin with Virgin Voyages until around 2 p.m.

On disembarkation day, guests don't have to leave their cabins until about 10:30 a.m. Many other lines want you off the ship by 8 or 9 a.m.

With most other cruise lines, you pay for internet and specialty classes — but everyone on Virgin Voyages ships gets access to unlimited WiFi and group fitness classes.

Crew gratuities, dining, and essential drinks like soda, sparkling water, and juice are included in the booking price. There's also no fuel-supplement charge, which many cruises have.

Once you pay your cruise fare, the only things to consider are optional add-ons like excursions, cocktails, and spa services.

Instead of unlimited drink packages, Virgin Voyages uses an onboard credit system called Bar Tab. Before the trip, you buy Bar Tab credits to dip into debit-style when you buy an alcoholic or a barista-made specialty drink.

Virgin Voyages has a loyalty match program called Deep Blue Extras that unlocks great bonuses, like free laundry services and extra Bar Tab funds.

Passengers who have loyalty status on lines like Carnival, Celebrity, Disney Cruise Line, Holland America Line, Norwegian Cruise Line, Oceania Cruises, Princess, and Royal Caribbean can basically apply to transfer their status to Virgin Voyages.

Additionally, if you're traveling with a group that books two or more cabins, you can link your bookings as part of Now We're Voyaging Together. Each cabin gets a free bottle of bubbly.

On many cruises, specialty dining will cost you extra. But, on Virgin Voyages ships, all of the 20-plus restaurants can be visited at no extra cost.

Unlike on most cruises, there are no assigned seats, and you don't have to share a table with strangers every night.

Dining times are also pretty flexible, and some eateries are open late.

Diner & Dash serves diner-style breakfasts all day, and Virgin Voyage ships have ShipEats, a 24-hour room service.

There are more than 10 group fitness classes offered daily, and you can take as many as you wish at no extra cost.

There are classic classes like spin and yoga, but you'll also find unique ones with bungee cords and retro-inspired aerobics.

That said, many classes fill up within hours on embarkation day. You can't book classes before boarding, so try to reserve your favorites the minute you set foot on the ship.

There aren't typical formal nights on Virgin Voyages cruises, but you'll definitely want to prepare for Scarlet Night.

Each cruise celebrates it from bow to stern with festive decorations and one-night-only activities like photo booths and a pool party.

Nearly everyone on board wears red for this event, so be sure to pack some if you cruise with Virgin Voyages.

The nightly shows are not typical song-and-dance affairs you see on other ships. Here, you'll find everything from naughty game shows to drag performances.

Don't sleep on shows with perplexing names like "The Miss Behave Show" and "Untitled DanceShowPartyThing."

Instead of trying to understand what the performances are ahead of time, just suspend disbelief, release your inhibitions, and enjoy.

Also, be on the lookout for roving performers, including magicians and sketch artists, who appear in public venues.

Some of them even extend invites to secret gatherings. I was once invited to a 30-minute magic show in the crew bar.

Even cooler? Many Virgin Voyages ships also have tattoo parlors, karaoke lounges, and record shops.