Aliwal Shoal · South Africa · Cave & cavern · Reef

Cathedral

Yellowmouth, honeycomb and salt-and-pepper morays hold in the cracks.

Area photo: Georgina Jones · CC BY-SA 4.0

Cathedral is a round pothole cut into the edge of Aliwal Shoal's tabular reef on its northern seaward side, roughly 20 metres wide, with a stone bridge spanning the eastern rim. The reef top around it lies at about 24 metres and the floor of the hole at about 29. Through winter, several ragged-tooth sharks take up residence inside it.

Where it is and how deep

Depths on a shared scale to 40 m (130 ft); dashed lines mark common certification limits.

30.2644° S, 30.8276° EPublished position for this site.

The dive

The site sits on the northern seaward side of the shoal and can only be reached by boat, about 7.2 kilometres from the launch at the Mkomazi River mouth or 6 kilometres out from Scottburgh main beach. You drop onto the surrounding reef top at about 24 metres and swim to the rim of the hole, a roughly circular opening some 20 metres across cut into the edge of the tabular reef, with a stone bridge carried over its eastern side.

The floor of the hole is at about 29 metres. Its walls carry encrusting and staghorn hard corals, branched black corals, a red sea fan with purple polyps, yellow whip coral and green tree coral, and yellowmouth, salt-and-pepper and honeycomb morays hold in the cracks. Raggy scorpionfish and paperfish sit still on the rock; goldies, emperor angelfish, clown triggerfish and yellow snappers work the water above it. In winter several ragged-tooth sharks inhabit the Cathedral, and the rule there is simple: do not startle, threaten or touch them. Water is about 21°C and visibility may exceed 15 metres.

Marine life and season

Sand tiger sharks

Month-by-month season rating for Cathedral
Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Good	Good	Good	Good	Good	Good	Prime	Prime	Prime	Prime	Prime	Good

Season follows Aliwal Shoal: The reef is dived all year round; ragged-tooth sharks congregate from July to November, bull sharks gather from December to April.

Know before you go

Ragged-tooth sharks share the hole in winter. They are not considered a significant hazard to divers who do not molest or startle them, so keep your hands in and let them move first.
The bottom of the hole is at about 29 metres, so bottom time is short, and the shoal's current can be running across the reef top when you come back over the rim.

Dive videos

Diving Cathedral (Aliwal Shoal) South-Africa.m4v · Mark Marais on YouTube

Questions divers ask

How deep is Cathedral at Aliwal Shoal?+

The reef top around the hole is at about 24 metres and the maximum depth is about 29 metres, so the dive sits in that band throughout.

How do you reach Cathedral?+

By boat only, about 7.2 kilometres from the launch site at the Mkomazi River mouth or 6 kilometres out from Scottburgh main beach. The site is inside the Aliwal Shoal Marine Protected Area, so a permit is required for access.