Cruise lines are trained on how to win over all those travelers who consider a vacation at sea too confining, limited or old-fashioned. They've even gone so far as to tone down decor and reword brochures.

Here's some of what you'll see in the coming year on the high seas — and rivers, too. River cruising remains popular and a good way to venture into new-destination territory. Thanks to CruiseCritic.com and Cruise Planners for their trend info.

Accessible travel

Royal Caribbean International was the first cruise line to receive Autism Friendly Certification by Autism on the Seas for inclusive programming designed to accommodate children with autism. Increasingly, those in wheelchairs or with other special needs will find shore excursions catering to their requirements. Cruise Planners has made a commitment to train travel agents on the best way to help clients through its relationship with Special Needs at Sea; the company offers mobility equipment rentals at departure facilities. Also, many new cruise ports are being designed with accessibility in mind; ask your cruise agent before your trip.

Booking ahead

Reflecting the trend of their land counterparts, cruise lines are seeing a trend toward bookings further in advance — almost a year out, according to Cruise Planners. So if you're thinking of sailing, get on it.

Redo, not new

Cruise lines are refurbishing old ships rather than buying new ones. Holland America is spending $350 million to upgrade entertainment, accommodations and dining fleetwide through 2018; Norwegian is spending $400 million on its Norwegian Edge program, focused on raising the quality of dining, cabins and public areas across the fleet; Crystal Symphony is getting a major makeover this year, and Silversea's Silver Cloud will transform from a cruise ship to an expedition vessel.

Pop culture themes

AMC's "The Walking Dead" and HGTV's "Property Brothers" have made a splash in the industry, and Cruise Critic predicts that there will be more of these themed sailings; fans love being able to rub shoulders with their favorite TV stars, personalities and musicians.

Suite life

More lines are offering an opportunity for exclusivity aboard their ships. Royal Caribbean International's new Royal Suite Class, for instance, includes not only butler service, but a dedicated concierge desk as well as special areas and a restaurant just for this premium cabin category.

Private ports

Once just a novelty, it seems most cruise lines are now in the private-island business. The latest entry is Norwegian Cruise Line's newest port of call, Harvest Caye in southern Belize, which takes advantage of the world's second-largest barrier reef. Carnival Cruise Line is now sailing to a new port, Amber Cove, in the Dominican Republic, and guests can sip cocktails poolside, shop for souvenirs and rent private cabanas at this private port. By the end of the year, MSC Cruises will begin sailing to the new Ocean Caye, an exclusive 95-acre island in the Bahamas with an emphasis on cultural authenticity and marine conservation. MSC ships will dock overnight at the island, giving guests a chance to enjoy evening entertainment and nightlife.

Expedition cruising

Celebrity Xperience and Celebrity Xploration will begin sailing to the Galapagos islands, and Lindblad Expeditions will position its new National Geographic Quest in Alaska and the Pacific Northwest. Look for major growth in expedition cruising over the next five years.

Cruise bundles

Travelers are customizing vacations, paying in advance for packages that, along with the cruise, include pre- or post-stays, plus airfare, and even the onboard internet and a drink package. That makes less to worry about once you embark and shift into vacation mode.

Active ashore

Most river cruise lines now have bikes — passengers in port can go off on their own or use them for guided tours. Lines such as AmaWaterways, Uniworld, Emerald and Scenic have hiking and kayaking tours. Meanwhile, Avalon has developed an entire Danube itinerary that focuses on active pursuits, and it plans to add a similarly dedicated itinerary on the Rhine next.

Redesigning for millennials

Trying to capture the attention of older millennials who have vacation time and disposable income, cruise lines have begun turning their attention to more refined offerings such as wine and food pairings, overnights with immersive port experiences and decor that's decidedly less busy and more refined. Some new ships are designing cabins to look more hotel-like, even changing their wording to call their cabins and staterooms the more ambiguous "accommodations."