Tourists swim in Ain Razat, a water spring in Salalah, Dhofar province, Oman August 20, 2016. Picture taken August 20, 2016. REUTERS/Ahmed Jadallah - RTX2NFGK

Image used for illustrative purpose. Tourists visit a cave at Ain Razat, a water spring in Salalah, Dhofar province, Oman August 20, 2016. Picture taken August 20, 2016.

Tourists gather around a natural fountain at Al Maghseel beach in Salalah, Dhofar province, Oman August 22, 2016. Picture taken August 22, 2016. REUTERS/Ahmed Jadallah - RTX2NFGE

Tourists boat at Wadi Darbat in Salalah, Dhofar province, Oman August 21, 2016. Picture taken August 21, 2016. REUTERS/Ahmed Jadallah - RTX2NFMJ

Image used for illustrative purpose. A general view shows Al Maghseel beach in Salalah, Dhofar province, Oman August 22, 2016. Picture taken August 22, 2016. REUTERS/Ahmed Jadallah - RTX2NFK8

Tourists boat at Wadi Darbat in Salalah, Dhofar province, Oman August 21, 2016. Picture taken August 21, 2016. REUTERS/Ahmed Jadallah

Image used for illustrative purpose only. Tourists visit a cave at Al Maghseel beach in Salalah, Dhofar province, Oman August 22, 2016. Picture taken August 22, 2016. REUTERS/Ahmed Jadallah - RTX2NFGH

Tourists boat at Wadi Darbat in Salalah, Dhofar province, Oman August 21, 2016.

Image used for illustrative purpose. Tourists enjoy a picnic at Wadi Darbat in Salalah, Dhofar province, Oman August 21, 2016. Picture taken August 21, 2016. REUTERS/Ahmed Jadallah - RTX2NFK9

Tourists visit waterfalls at Ayn Athum in Salalah, Dhofar province, Oman August 23, 2016. Picture taken August 23, 2016. REUTERS/Ahmed Jadallah

Tourists visit a cave at Ain Razat, a water spring in Salalah, Dhofar province, Oman August 20, 2016. Picture taken August 20, 2016. REUTERS/Ahmed Jadallah - RTX2NFGN

A tourist lifts up a boy as they visit waterfalls at Ayn Athum in Salalah, Dhofar province, Oman August 23, 2016.