Diving the south coast of South Africa/Alphard Banks

Understand

Alphard Banks is the southernmost recreational dive site on the continental shelf of Africa.

Position 1 Alphard West Pinnacle: S35° 02.395' E20° 51.856' (16 m) This site is in the Agulhas Bank Complex Marine Protected Area (2019). A permit is required.

Name "Alphard" is the name of the brightest star in the constellation of Hydra, the banks are indirectly named for this star, possibly via a ship of the same name.

Depth Maximum depth is about 80 m. and the top of the Western pinnacle is about 16 m. Average depth of a dive (excluding decompression) is likely to be more than 25 m.

Visibility Visibility can be excellent. More than 30 m is possible, and it can be better at depth than near the surface.

Topography The banks are an eroded seamount, the core of an extinct volcano. The top of the western pinnacle is between about 20 to 30 m deep around the edges of the drop-off, which is quite steep, mostly more than 45 degrees, with occasional vertical cliffs and small overhangs. Geology: Volcanic rock, probably Palaeocene, about 58(±2.4) million years old, of the Alphard Tertiary Igneous Province.

Conditions

The site is exposed to the weather, wind waves, and swell from all directions, so should be dived when the weather and sea state forecast is good. Water temperature may vary with depth. In April 2021 the surface temperature was 20°C, dropping to about 19°C on the reef top, but 11°C below the thermocline, which was somewhere around 40 m deep. There was a distinct improvement in visibility in the water below the thermocline (more than 30 m), although the shallower water was quite clear (about 20 m), with only the surface obscured by ctenophores. This may not be common.

Getting there

This is a boat dive. The site is about 78 km from Struisbaai Harbour, where there is a public access slipway, or 74 km from Infanta and the Breede River estuary. The Breede River mouth is nearer to the Alphard Banks, and the anchorage is well protected, but the mouth of the estuary is tricky to navigate. Struisbaai anchorage is more exposed to the prevailing swell and winds from the south east, but the slipway is fairly sheltered and the approaches are uncomplicated if one keeps well clear of the shallow reef east of Northumberland Point.

See

Marine life Kelp forest, sponges and small sea fans. Fish include yellowtail and several species of seabream.

Features Deep, steep walls with ledges and occasional overhangs.

Photography On a day with good visibility and bright sunlight, wide angle with natural lighting could give spectacular scenic shots, and with artificial light, wide angle equipment should work well for closer views of the reef. Macro equipment will almost always produce good results.

Suggested routes Drop in at the top of a wall, go to your chosen maximum depth and work your way up the wall to the nearest pinnacle. Surface on a decompression buoy, so the boat can keep track of your position.