The U.S. Marine Corps is working on the design of its next generation of amphibious ships. Mostly the marines are looking for bigger ships with a more efficient layout. But two new ideas are interesting, for different reasons. One proposal is to build a few amphibious ships that lack the flooded well in the rear of the ship for amphibious craft. Such an amphibious ship would depend entirely on MV-22 tiltrotor and helicopters to move marines to shore objectives. Some F-35B vertical take off jet fighters would be aboard as well. The navy has such ships before, in the 1960s, but the marines decided that the ability to handle amphibious tanks and boats was still needed. But times have changed, and the aircraft are more powerful (especially the MV-22 Osprey) and the missions more often call for a small number of marines to be placed somewhere inland in a hurry.
The other change is the deletion of climate controlled exercise and weight rooms. This was not to keep the troops comfortable during their work outs. The theory was that the Marines could do their work-outs under conditions of temperature and humidity similar to the that normal in the areas where they were likely to be deployed, and thus become acclimated to doing hard work in the local environment. It turned out not to work. The time spent in the environmentally correct work-out rooms was not enough to make a difference. So the newer ships dont have the special equipment, which saves some money.