This Unesco World Heritage Site is home to the earliest prehistoric whale fossils ever discovered. The more than 400 basilosaurus and dorodontus (both rather fierce water predators) skeletons found here are around 40 million years old and show the clear evolution of land-based mammals into sea-going ones, as they have vestigial front and back legs. The sands are also studded with the remains of manatees and big bony fish – which look very out of place in the vast desert. From the central site complex a small network of walking tracks leads out to more than a dozen skeleton sites. Although it doesn't sound like much, the desert setting is dramatic and it's a great destination for a day or overnight outing, usually combined with Wadi Rayyan. The site complex has toilets, a wilderness campground and the excellent Wadi Al Hittan Fossil & Climate Change Museum. The circular one-room museum does a good job of explaining the geological history and nature of the area with a series of information boards and fossil displays that surround the crowning exhibit, an 18-metre long skeleton of a Basilosaurus Isis whale. There's also a short documentary on Wadi Al Hittan. Wadi Al Hittan is reached by an unsealed corrugated desert track that runs off the main Wadi Rayyan road; a 4WD is necessary. From the turn off, it's 37 kilometres to the main site complex.