Ras Madrakah is an excellent day-trip opportunity for anyone visiting Duqm or on the way to Salalah (through Hasik).
The place offers fantastic camping spots overlooking black mountains and golden sand beaches. Also great bird spotting and off-roading, with nice weather even during the hot summer months.
Oman has several places where you can find pink lakes. There are two tricky bits before you get disappointed. The first one is that they are not always pink and that depend on the weather, tides, or season. And the second one is that they are best enjoyed from the air.
This is a place that I would highly recommend visiting for any nature lover living in Oman. You will spend at least 5 hours driving there from Muscat, so plan your escape well.