As you speed along the ship's top-deck raft ride, waves break at the ocean's surface 150 feet below. It's an acrophobe's nightmare -- and could be the most thrilling moment of your next cruise vacation.

We've come a long way in the century since the Titanic, when that ship's heated swimming pool was a mind-boggling luxury. Now it's AquaDuck, the cruise industry's first water coaster, that's making a splash on board the Disney Dream and Disney Fantasy.

It takes pluck to stare down the AquaDuck and the rest of the world's craziest, record-breaking water slides. Some, like Brazil's 135-foot-high Insano, are traditional body slides, while others resemble intricate roller coasters and showcase innovation in water slide technology and design. Read on for more of the loopiest, crowd-pleasing water slides around the globe.

RideHouse

Where: Happy Magic Water Cube Waterpark, Beijing

When news broke that the cutting-edge Beijing National Aquatics Center (aka the Water Cube) would be converted into a theme park, expectations were high. And sure enough, China's first themed indoor water attraction debuted in 2011 tricked out with valves, cranks, jellyfish, buckets, water cannons, giant bubbles, climb nets and spray tubes -- and that's the short list of design elements.

Crazy Fact: RideHouse is made up of 12 slides (the most of any water-play structure in the world) and boasts its own giant water-filled cube that periodically soaks those waiting for their turn.

Toboggan

Where: Città del Mare Hotel Village, Palermo, Italy

Eleven slides form Sicily's most scenic water attraction, which runs down a cliff on the northwest coast of the island. On a sun-drenched summer day, the turquoise slide, which is open to guests of the resort, complements the clear-blue waters of the Gulf of Castellammare -- the end point of Toboggan. Keep your eyes open: The slide passes three decks, and each level delivers spectacular views of the 67-acre property.

Crazy Fact: A full top-to-bottom journey down this seaside slide will send you into four separate bodies of water: three pools and the Mediterranean Sea.

King Cobra

Where: Six Flags Great Adventure, Jackson, New Jersey

The king cobra is the world's longest venomous snake, so it makes sense that this eponymous ride, which opened in July, promises to be one of the craziest theme-park attractions. Resembling a massive cobra, the ride makes an intimidating first impression with its oversize black, yellow and bold orange scales and allows two tubes to zip up to 32 mph.

Crazy Fact: The ride's finale features a sudden 25-foot drop at a 50-degree angle that creates the illusion of riders being swallowed by the king's massive mouth.

Wild Vortex

Where: Wilderness at the Smokies, Tennessee

This water-park resort has indoor rides -- with a giant glass roof -- that keep the thrills coming all year long. But adrenaline junkies will want to head outdoors for the newest challenge: the 66-foot-tall Wild Vortex, which debuted in June.

While the ride lasts only seven seconds, don't underestimate the rush you can get from its sharp vertical plunge and a gravity-powered loop-the-loop, which riders experience at a 2.5 g-force.

Crazy Fact: Don't like surprises? Well, be warned that the first 39-foot free fall is initiated by the sudden release of a trap door.

Behemoth Bowl

Where: Chimelong Water Park, Guangzhou, China

Seated face-to-face on four-person rafts, riders reach speeds of 32 feet per second as they plummet down a 262-foot-long translucent tunnel and into a 60-foot-wide bowl (the world's largest). After multiple spins, riders are dropped through a central chute and into a large splash pool.

Crazy Fact: A YouTube search of bowl slides turns up videos of unsuspecting riders getting stuck in the "drain." Not on this slide. ProSlide's patented CorkScrew™ exit system is the ride's essential design component and ensures a safe ejection. Phew.

Insano

Where: Beach Park, Aquiraz, Brazil

Brazil's 135-foot attraction stands out from the crowd, even if it's not quite the tallest waterslide to make our list (Italy's 197-foot Divertical takes that title). Riders are certainly impressed and wait in line to brave that infamous 14-story drop. And you can expect those lines to get longer: In 2011, Brazil's largest water park hosted 788,000 visitors, which represents a 7% increase from the prior year.

Crazy Fact: The singular sharp slope produces a rapid descent; Insano plunges at a speed of 65 mph, taking riders from start to heart-pounding finish in less than five seconds.

Divertical

Where: Mirabilandia, Ravenna, Italy

Say hello to the world's tallest water ride: the $26 million Divertical, which officially debuted in June. The coaster features a one-of-a-kind elevator lift system that brings 10-person boats to the top of the 197-foot-tall attraction. As they slide along a roller coaster track, riders face drops, hairpin turns and then an oversize splash pool at the finish line.

Crazy Fact: The initial plunge takes you through a 45-degree water flume at more than 65 mph.

Wiegand Maelzer Slide Tower

Where: Area 47, Tyrol, Austria

This stainless-steel lakeside attraction showcases flawless craftsmanship -- not to mention a handful of pretty extreme slides. After climbing up the 90-foot tower, riders have their pick among five, including a 328-foot-long chute with an added jump section at the bottom.

Crazy Fact: The tower is also fitted with five diving boards (at 6.5, 16, 33, 66 and 91 feet high), though the tallest two are reserved for professional divers.

Leap of Faith

Where: Aquaventure Water Park, Atlantis Paradise Island, Bahamas

This 60-foot-tall, nearly perpendicular slide cascades down a life-size replica of a Mayan temple -- the hallmark of the resort's 140-acre waterscape. But for many, the real "leap of faith" occurs after the initial drop when you're subsequently propelled through a clear acrylic tunnel in a shark-infested lagoon.

Crazy Fact: In 2008, a female reef shark vaulted out of its tank and landed on the slide. While no resort guests were harmed (the water park had yet to open for the morning), the shark could not tolerate the chlorinated water and died shortly afterward.

Cliffhanger

Where: Schlitterbahn, Galveston, Texas

The park's crowd-pleasing attraction, which debuted in 2007, was part of a significant expansion -- and Cliffhanger still stands as the tallest and steepest ride among all four Schlitterbahn parks in the U.S. Like Summit Plummet, this single body slide consists of an alarming vertical drop. After being propelled from the top of the tower, riders plunge nearly 81 feet at speeds of up to 35 mph.

Crazy Fact: The Cliffhanger is designed as an open chute, so you'll be fully aware and exposed every second of that free-fall drop.

Mammoth

Where: Holiday World and Splashin' Safari, Santa Claus, Indiana

The $5.5 million Wildebeest ride, a high-speed hydromagnetic water coaster that uses linear induction motor technology, put this water park on the map in 2011. Holiday World continues to expand with Mammoth, a slide towering seven stories and stretching more than three acres -- making it the world's longest water coaster. (Wildebeest takes second place.)

Crazy Fact: Six-person rafts are propelled up and down hills in 12-foot-wide channels. There are five enclosed slide sections, which means you'll be doing that twisting and shouting in the dark.

AquaDuck

Where: Disney Dream and Disney Fantasy cruise ships

Meet "the Duck" -- the cruise industry's first-ever shipboard water coaster. The 765-foot-long, four-deck-high AquaDuck debuted on Disney Dream in 2011 and has since been added to Disney Fantasy. Atop the aft deck, passengers hop on a two-person inflatable raft that is then propelled forward by high-powered water jets. Expect to be dropped, looped around and accelerated.

Crazy Fact: After the initial drop, riders are thrust through a clear acrylic "swing out" flume that extends 12 feet over the side of the ship -- and 150 feet above the ocean's surface.

Mount Gushmore's Summit Plummet

Where: Blizzard Beach at Walt Disney World, Orlando

The first thing you see when you enter Blizzard Beach is 90-foot snowcapped Mount Gushmore, the world's most photographed faux-mountain and home to one of the fastest free-fall speed slides. From the Summit's ski jump tower, riders take a vertical plunge straight down to the base of the mountain.