Is an olympic swimming pool heated?

Yes, Olympic Swimming Pools (and all competitive swimming pools) are heated.

Olympic swimming pools are kept at temperatures typically around 77-79 degrees Fahrenheit or around 25-26.1 degrees Celsius. However, the temperature can go up to 82 degrees Fahrenheit or 27.7 degrees Celsius and be acceptable to FINA, the organization overseeing Olympic swimming.

FINA's optimal temperatures for Water Polo are 79 Fahrenheit or 26 Celsius; for synchronized swimming, 81 Fahrenheit or 27 Celsius; and for diving, not under 79 Fahrenheit or 26 Celsius.