The third floor features Yale’s 50-meter practice pool. Holding 331,000 gallons of water is to this day the largest above-ground swimming pool in the world. Supported by massive concrete and steel columns, and encased in 8” thick shell of 380 cubic yards of concrete and 42 tons of reinforcing steel, the pool posed a tremendous engineering problem for the architects. Foundation footing had to be designed to distribute the weight evenly over a wide area. In fact, when the pool was filled, engineers recorded a slight settlement of the entire structure. For fear that the supporting columns would break through the pool’s bottom when relieved of their burden, the water was not drained from the shell until 1954. Needless to say, the fear was unfounded.

The pool is partitioned by a moveable bulkhead, which can be set to different lengths to allow for water polo and various lap distances. It can also be moved to the far end, allowing the full 50-meter long course to be used; the pool itself is actually 55 yards long, accommodating the divider for 50-meter competition.

Until 1978, the pool contained a stainless steel bulkhead, which had weighed seven tons. Over the years, the copper air tanks, which were used for a ballast, gradually filled with water, and the bulkhead became increasingly difficult to move. By the late 1960s, it took over twenty people to move it. When it was finally dismantled, it had to be cut into sections with acetylene torches in order to be removed from the building.