Can women go swimming if no men are present and they cover in front of the siters? Our mosque in Adelade says no. Prove with Hadith and Qur'an.

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

There is no harm for women to swim or to go the swimming pools if the following conditions are met:
1- A woman should be covering her Awrah.
2- The place should free from mixing with men.
3- The other women at that place also should be covering their Awrah.
4- The place should safe in such a manner that men cannot see the women.
5- A married woman should take the permission of her husband for going there.
Allah knows best.