Wadi Shab's permanent watercourse — one of fewer than ten year-round flowing wadis in Oman — has carved a four-kilometre limestone gorge between Tiwi and Sur over millennia. The canyon's terraced pools, fed by mountain springs rather than seasonal rain, maintain turquoise clarity even through summer months when surrounding wadis run dry. Bimmah Sinkhole, thirty kilometres north, formed when the roof of an underground limestone cave collapsed roughly six hundred years ago, creating a forty-metre-wide basin now filled by a subterranean aquifer mixing fresh and seawater. Both sites anchor the Al Sharqiyah coastal corridor, where the Eastern Hajar range meets the Arabian Sea. Wadi Shab's lower canyon requires a brief boat crossing — fishermen ferry visitors across the final fifty metres where the wadi meets tidal water — before a forty-minute upstream hike through date palm groves and past terraced agricultural plots still worked by families from Tiwi village. The trail follows the wadi bed, crossing shallow water eleven times before reaching the first major swimming pool. A narrow keyhole passage at the canyon's upper end opens into a hidden chamber where a waterfall drops through a shaft in the rock ceiling. Bimmah Sinkhole's geological formation exposes the region's karst limestone layers, visible in the concentric rings of stone descending to the pool surface. Local tradition attributed the crater to a meteorite impact until geological surveys in the 1990s confirmed dissolution and collapse. The site's mineral-rich water supports unusual algae colonies that tint the pool jade-green in morning light, shifting to deep turquoise by afternoon as the sun angle changes. Wooden steps now descend to the water, replacing the rope system visitors used before 2008. Private excursions to both locations typically originate from Muscat, covering the hundred-and-forty-kilometre coastal route through fishing villages and date plantations. The journey passes Quriyat's fort ruins and the white-sand curve of Fins Beach before reaching Bimmah, then continues south to Wadi Shab. Most operators schedule morning departures to reach the wadi before midday heat intensifies in the narrow canyon, where shade disappears between eleven and three.