Looking to steer away from a conventional ocean cruise? Whether you're yearning for cultural immersion or slow-paced exploration in hard-to-reach ports of call, river cruising offers an intimate and leisurely alternative to a traditional ocean cruise experience. And it probably comes as no surprise that river cruising is on the rise — with increasing passenger growth rates year over year. In fact, the Cruise Lines International Association announced that member cruise lines will invest more than $4 billion in 22 new ships this year — 16 of which are river boats.Viking Cruises is leading the sea change, with 10 new Viking Longships set to launch this year — in addition to the 14 ships the company debuted last year. And demand continues to climb: From 2001 to 2015, Viking saw a 30 percent increase in North American passengers, while mainstream ocean liners saw just a 5 percent increase for the same period. Other river cruise operators — such as Tauck, which will add two new ships this year, and Avalon Waterways, which introduced a brand-new suite option on its ships for 2015 — are also catering to travelers' needs with high-tech amenities and a variety of itineraries across the globe.So, why is river cruising taking off? "River cruising gives you more time in the destination that you've come to visit as opposed to ship time," explained Richard Marnell, senior vice president of marketing at Viking Cruises. According to Marnell, river cruising allows travelers to interact with local cultures and, ultimately, broaden their perspectives with "an understanding and insight into the people and the life" of each destination.To help you decide whether a river cruise is right for you, U.S. News spoke with Marnell to identify the top six reasons river cruising is booming, along with what to expect once you climb aboard.In Pictures: 6 Reasons River Cruising is All the RageWhile many cruise lines offer all-inclusive rates that cover onboard expenses such as meals, lodging and activities, river cruises up the ante by bundling the cost of shore excursions, onboard entertainment and drinks into their fares, eliminating unexpected out-of-pocket expenses. "River cruising is a fantastic value for both time and money," explained Marnell, emphasizing that many cruise companies tend to offer an excellent lead-in price, but then tack on extra fees for everything from soft drinks to meals at specialty dining venues. Viking also offers complimentary Internet access (in private cabins and public spaces) and airport transfers. Other operators, like Uniworld and AmaWaterways, cover the cost of shore excursions, premium beverages and Wi-Fi capabilities in their all-inclusive rates. On a river cruise, travelers have the chance to steep themselves in off-the-grid destinations. While larger megaships typically require travelers to tender to shore, riverboats dock in town, making land-based exploration easier. And according to Marnell, guests stay stimulated every day with cultural, culinary and history-driven tours and activities. These experiences allow travelers to "experience something authentic to the region," he added. "We're taking you behind the scenes to places that most folks don't have access to," he said, pointing to Viking's school visits in China, where visitors can join daily lessons to embrace the local culture. Other shore activities can include anything from an after-hours visit at a world-renowned museum to exploring a colorful market with a local. And if you'd rather branch off and explore on your own, you have plenty of free time in port. Much like many luxury ocean liners, river cruises aim to connect passengers with local cultures both on and off the ship, with onboard lecture series and destination-inspired meals. But for travelers looking to embrace their surroundings, river cruises offer culturally influenced onboard enrichment activities like interactive cooking lessons and tastings based on the region visited that day. On a cruise through the Rhine Valley, for instance, Viking Cruise passengers are invited to attend expert-led talks highlighting the history of the French impressionists and famous castles of the region. And on journeys along the Nile, guests are offered onboard lecture series that provide historical and cultural context for Egypt's 5,000-year-old dynasties and artifacts. Meanwhile, AmaWaterways serves regionally inspired dishes and provides onboard entertainment from local performers. And Emerald Waterways offers culturally focused evening entertainment, such as folk music performances from a local Bavarian band, on its Danube sailings.See: 5 Not-To-Be-Missed River Cruise ItinerariesFor most of us, lodging can make or break a vacation. River cruise companies are taking note, rolling out large suite category staterooms featuring open-air balconies with sliding glass doors and other bells and whistles for guests. Viking's Longships maximize space and comfort with 205-square-foot Veranda category cabins that feature floor-to-ceiling sliding glass doors that open to a veranda, along with wardrobes, under-bed storage and eco-friendly features, such as solar panels and diesel electric hybrid engines. "We make better use of the square footage that is available to us, and that allows us to provide a better value to the customer," Marnell added. Other river cruising companies offer the luxury of a floating hotel, such as Tauck River Cruises with its Inspiration Class riverboats, which feature 300-square-foot loft cabins that stretch across two decks to provide unobstructed river views. Emerald Waterways' ships also offer high-tech cabin amenities, including flat-screen TVs, free Wi-Fi, Nespresso machines and iPads available for rental in the Owner's One-bedroom Suites.A main allure of river cruising is the intimate atmosphere. Carrying fewer than 200 passengers, river cruises allow for a higher level of personalization than what's experienced on the 3,000-plus passenger megaships sailing today. On a riverboat, you don't have to worry about wait times at meals, nor do you have to stand in long lines when embarking or disembarking from different ports.On a river cruise, you don't have to sweat the details: Once you choose your itinerary and cabin, everything is mapped out for you, eliminating the need to plan shore excursions, make reservations at specialty dining venues or stress over additional expenses since everything is covered in the all-inclusive rate. Plus, you don't have to be concerned about transportation expenses or whether you'll have enough time to absorb each destination. Another bonus: you can spot the shoreline at all times, and you never have to worry about a choppy passage — a top selling point for cruisers prone to sea sickness. "At the end of the day, it's for anyone who's seeking enrichment, education and immersion in their travel experiences," Marnell summed up. In Pictures: 6 Reasons River Cruising is All the RageAbout the author: Liz Weiss is an editor for the Travel section at U.S. News. You can follow her on Twitter, connect with her on LinkedIn, circle her on Google+ or email her at email@example.com.