A dark, daunting "bottomless pit" awaits daredevils on Royal Caribbean's Oasis-class cruise ships. The Ultimate Abyss is the tallest (and quite possibly the scariest) slide at sea. We took the plunge during an exclusive sneak peek -- and luckily managed to escape so we could share the experience.

What It Is

The Ultimate Abyss on Royal Caribbean cruise ships is not a waterslide; it's a pair of side-by-side, 216-foot-long slides that run 10 decks, from the Sports Zone (Deck 16) to the Boardwalk (Deck 6) at the back of the ship. Riders sit on special mats made to ease the glide and ensure they hit the average maximum speed (9 miles per hour). Each slide is a dark tunnel, equipped with flashing lights and an audio system that plays startling sounds all the way through to the finish near the AquaTheater. The slide is found on Harmony of the Seas, Symphony of the Seas and Oasis of the Seas; it will be added to Allure of the Seas in 2020.

Our Experience

We gave the slide a whirl in "far from normal" conditions (cold, dark, rainy), so rest assured: Ominous storm clouds aren't part of the special effects.

When we arrived at the slide on Harmony of the Seas, we were greeted by a monster-like fish with big eyes and fangs. (Google "Fangtooth" to see what we mean.) The entrance to the Ultimate Abyss slide is through the fish's mouth. Crewmembers escorted us up a short flight of stairs to a glass-plank floor with views of the 100-foot drop below. That's when the heebie jeebies kicked in.

At the top, there are three options: scream and turn around, get into the slide and give yourself a motivational pep talk, or look down and marvel at the view below. It's definitely not for the faint-hearted. From this vantage point, the Boardwalk and AquaTheater looked so small; with the ocean even farther below, it really put into perspective how high we were above sea level.

Staffers then helped us get situated on our mat, which worked sort of like a sit-in kayak in that you slip your legs into a covered tip, then hold onto a handle and lean back. We kept one sweaty palm on the handle and used the other to grip the top of the slide for support. Our heart was pounding; we had no idea what would happen once we let go. The crewmembers gave a quick motivational speech and assured us we wouldn't "fly off into the ocean" (a question we had to ask on behalf of some of our more skittish readers). As soon as we felt comfortable, we got the "okay" to push off the slide, held onto the handle for dear life and immediately sped away into the darkness.

Once we got going, we forgot to be scared -- and began to have fun. As we slipped and slid, we realized were were picking up speed but never once felt like we were about to lose control. It was evident the mats were custom-made for this slide; we felt secure and centered the whole way down. To add to the adrenaline-powered thrill, the slide put on a show with funky lights and eerie, echoing sounds that popped up out of nowhere. Imagine startling Halloween soundtrack-esque shrieks and wind gusts. At one point, we even felt like something was following us. Meanwhile, trippy lights and twinkling stars splashed against the slide's purple frame -- it was only pitch-black for a second -- and we suddenly had a flashback to riding Space Mountain at Disney World. The effects carry on throughout the ride, which, despite going so fast, didn't end in the blink of an eye like other rides we've experienced. Of course, when we came out on the Boardwalk, breathless and laughing, we wanted to do it all over again.

Worth a Try?

It's definitely worth a try, as long as you can make it past the glass plank. (If you're deathly afraid of heights, this isn't the ride for you.) There's also no need to worry about that queasy feeling you get after a straight drop. We never felt the notorious butterflies, and while we can't speak for everyone, we will stress that the ride isn't meant to feel like a roller coaster. Its twist-and-turn design allows you to enjoy the speed and special effects without the stomach churn.

Things to Note

Riding Royal Caribbean's Ultimate Abyss is free, but it does have height restrictions. Check your daily Cruise Compass for operating hours. Screaming (or swearing) down the slide is inevitable -- and totally acceptable. Just be mindful that whatever you say in the tunnel doesn't necessarily stay in the tunnel; sound echoes down the slide and can be heard by passersby if they listen closely. (Thankfully, the Boardwalk is usually bustling.) Our "What the heck is that?!" screams made for a fun conversation starter with those lingering by the slide exit.

Video Transcription

Hey, guys! It's Gina Kramer from Cruise Critic, and I'm here onboard Harmony of the Seas, about the take the plunge on Ultimate Abyss. This is the tallest -- and quite possibly the scariest -- slide at sea, and I'm going to go check it out and let y'all know how it goes. Ready to go?

Oh my God. [screaming] Oh my God. What ... what the heck is that? Oh my God! [laughing] Oh my God. [shrieking]

That was amazing. Okay, guys. So this thing started up at the sports deck; it's 10 decks high, and it drops you right down here by the AquaTheater. Um, again, my advice? Don't look down when you're on the plank, but you're going to have a blast either way. Now I dare you to go try it out for yourself.