Elphinstone Reef lies approximately 30km north of Marsa Alam, 15km offshore in the southern Red Sea. It is a narrow, cigar-shaped reef roughly 350m long, oriented north to south, rising steeply from the sea floor to just below the surface.

The reef has three distinct areas. The south plateau, the more famous, sits at around 18–22m, a wide shelf of soft coral and gorgonian fans that drops sheer on both the east and west sides to beyond 100m. This is one of the most reliable sites in the Red Sea for oceanic whitetip sharks: year-round residents that appear from the blue and work the plateau at close range, particularly in the morning before the day boats arrive. Peak season runs September to November, when multiple animals can be present simultaneously. At the very southern tip sits the Elphinstone Arch, a tunnel connecting the east and west walls at around 50m depth. It is a technical dive in every sense: you need to descend to 50m just to see it. Recreational divers do not dive the arch.

The north plateau sits at around 25–30m, broader and less current-swept than the south, with good soft coral coverage on both walls. The defining feature here is the crack: a fissure in the reef floor at around 30m that opens onto a third plateau some 20m below. Hovering above it is one of the most distinctive moments in Red Sea diving, like looking out from a balcony into open blue, with the structure falling away beneath you. Going through the crack and descending to the third plateau is below 30m and is a technical dive; recreational divers stay above and look down.

The east and west walls run the full length of the reef, covered in soft coral, sea fans and gorgonians from the surface to well beyond recreational depth. Both walls are diveable as drifts, current tends to run north to south, making the east wall the more sheltered option in heavy current. Unlike Daedalus and the Brothers, Elphinstone is accessible as a day trip from Marsa Alam. Most liveaboards covering the southern Red Sea include it on route.