double check that math - olympic pool is 50x25x2 meters, or 2500m3. 1 m3 of water is roughly 1 metric ton (1 g/cc = 1 kg/L = 1 t/m3) depending on temperature and such.
Whoops, yeah, made a few mistakes. Next time I'll do the usual and open a throwaway spreadsheet. Also, picking gallium-density from a slightly higher temperature where it's liquid.
57000000g / 5.9 g/cc = 9661017 cc = 9.661m3