Mnemba Atoll · Tanzania · Wall · Reef
Big Wall
A vertical face from 18 m to 50 m, cut with caves and overhangs
Area photo: Jorge Láscar · CC BY-SA 2.0
Big Wall is a vertical face in open ocean east of Mnemba Island, dropping from 18 metres to 50 metres in clear water. Caves and overhangs are cut into it along its length, and pelagics are spotted off the face occasionally. PADI's listing is the only published description of the site, and no current or visibility figures are published for it.
Where it is and how deep
5.8078° S, 39.4187° EPublished position for this site.
The dive
The wall starts at 18 metres and falls vertically to 50, so depth is a decision made in the first minutes rather than something that creeps up on you. The face reads as one continuous surface in water the published description calls crystal clear, which strips out most of the landmarks you would otherwise use to hold a level and makes it easy to sink deeper than planned. Agree a hard limit on the boat and watch the computer rather than the rock.
Caves and overhangs are cut into the wall along its length and they are what the dive is spent on: in and out of the shade, then back out to look into the blue, where pelagics are occasionally seen off the face. No route, no current figure and no visibility figure is on record for the site, so the shape of the dive is whatever the guide runs on the day. The one thing the description fixes is that there is nothing underneath the wall until 50 metres.
Marine life and season
The sources we used don't single out particular species here.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Prime | Prime | Good | Off-season | Off-season | Fair | Good | Good | Good | Prime | Prime | Prime |
Season follows Mnemba Atoll: Jul–Mar is divable, with Dec–Feb calmest and clearest; the long rains in April and May bring poor visibility and rough crossings.
Know before you go
- The face falls to 50 m with nothing underneath it, so agree a hard depth limit on the boat and hold it: there is no bottom to arrest a slow descent.
- The caves and overhangs are easy to swim into and lose the open water from; stay in daylight and keep the exit in sight.
Dive videos
Diving Big Wall, Mnemba, off Nungwi, Zanzibar · Vance Stevens on YouTube
Questions divers ask
How deep is Big Wall?+
The wall starts at 18 metres and drops vertically to 50 metres, which PADI lists as the site's maximum depth. A recreational dive is run in the upper part of that range.
Is Big Wall suitable for beginners?+
No. The face begins at 18 metres and continues past recreational limits to 50 metres in open ocean, so it needs a diver comfortable holding a set depth against a vertical reference.
Sources
- Big Wall Dive Site, Zanzibar, Tanzania — PADI
- Mnemba Island — Wikipedia
In The Logbook
- The best wall dives in the worldWalls & drop-offs · 11 min read
- How much weight do you need to dive?Gear & kit · 8 min read
- Why is the sea blue? Water filters out redOcean science · 7 min read
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Wall
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