If you get vertigo on a normal roller coaster, you'll definitely get vertigo on this roller coaster. The Carnival Mardi Gras is currently in construction in Finland and is on track to be the cruise line's largest ship yet, able to hold 5,200 passengers. Perhaps most notably, the ship features an 800-foot long electric roller coaster that travels at speeds up to 40 mph. That's just one of the many over-the-top amenities planned for the massive ship. The future of cruising certainly looks promising.