In the past few years, we have covered plenty of shipping container projects here. You can use them to build an office, extra room, or even a pool. Shipping Container Pools makes custom pools that meet your needs. This particular one has a 8m window.
These shipping container pools can be ordered in 6m and 12m sizes. They are about 1.3m deep. You will need to place these on a steel frame or concrete slab.
More information is available here.