Burqini

"The Burkini is a newly invented modest swimwear for traditional Muslim women who want to hang at the beach, but do not want to let it all hang out like their western counterparts. Approved by clerics and modeled on the modest Muslim covering for women called the Burka, the Burkini gives a newfound freedom to these Muslim women who want to have fun and frolic in the waves. Its design also allows Muslim women to now take part in the rigorous training required to be lifeguards on Australia's famous Bondi Beach in Sydney.
It is designed by Ahiida, a company in Australia."

Just choose between the slim fit (photo) or modest fit.