When I sailed Mercury the ship wasn't full and I found the gym and its equipment more than adequate. They have all sorts of machines both aerobic and strength training. They have lots of free weights and benches. They offered really high end step aerobics. I stuck with the machines. It wore me out just looking at the step aerobics class. The gym is on the top of the ship with great sea views and right next door to the AquaSpa so you can work out the kinks when you finish exercising.