The dive site Finlay's Deep or Mont Blanc is an offshore rocky reef in the Castle Rocks restricted area on the False Bay coast of the Cape Peninsula, near Cape Town in the Western Cape province of South Africa.
This is a small reef with a large number of Gorgonian sea fans.
- S34°15.005' E018°29.194' 1 Finlay's Deep: About 900 m directly offshore of Finlay's point
This site is in a Marine Protected Area (2009). A permit is required. The site is entirely inside the Castle Rocks Restricted Zone.
The name "Finlay's Deep" is a reference to Finlay's Point inshore, and that the reef is relatively deep. The alternative name is “Mont Blanc” as the top of the main granite boulder appears white as if snow-covered.
Maximum depth is about 30 or 31 m and the top of the reef is reported to be about 20 m.
The reef is a narrow outcrop of granite about 37 m long from north east to south west on an axis of 39°magnetic, and about 7 m wide. The reef is notched by a number of fairly deep cracks, but mostly they are not very wide, The highest point is only a few metres shallower than the sand bottom which is at 30 m. Some sections of the reef are quite low, in the order of 1 m at the north end. There appears to be another outcrop slightly further offshore, probably about 5 to 10 m to the east, of unknown extent.
Geology: Late Pre-Cambrian granite of the Peninsula pluton.
The site is exposed to swell from the south east, and to a certain extent, from the south west. Longer period swell will make conditions on the reef uncomfortable due to strong surge, but short period waves will just make it uncomfortable on the boat. Visibility is less predictable, and at this time is largely a matter of luck and reports from divers who were in the area recently.
The site is usually at it's best in winter but there are also occasional opportunities at other times of the year, though least often in summer, when the south east wind tends to blow much of the time.
The most obvious group is gorgonian sea fans. There are large numbers of Palmate, Sinuous, Flagellar and Multicolour sea fans present but not very big. The surface of the rock is encrusted with Mauve sea cucumbers, Strawberry anemones and sponges, with a scattering of Elegant feather stars and Striped anemones.
The site is usually dark due to the depth, so anything other than macro will require an external flash.
No particular route recommended. The reef is small enough to explore on a single dive. If you have time left you might explore to the east of the southern end in case there is more reef in that area.
The site is quite far offshore, and the area is often dived in an offshore wind, so there may be a risk of getting lost on the surface if the wind comes up strongly.
Certification appropriate to the depth will be expected, but no special skills are required. Ability to deploy a DSMB may be useful.
No special equipment is required, but a DSMB will be useful if you have to surface away from the shotline.
- 1 The Jambles
- 2 Graeme's Spot
- 3 Finlay’s Point
- 4 Finlay's Pinnacle
- 5 Carnaby Street Pinnacle
- 6 Atlantis Reef
- 7 Sherwood Forest
- 8 Fish Tank
- 9 Partridge Point - Seal Rock
- 10 Partridge Point - Deep Partridge
- 11 Partridge Point - Dave's Caves
- 12 Partridge Point - Big Rock
- 13 Partridge Point - Peter's Pinnacles