Rosco’s Ridge: New Cenderawasih Bay dive site

by Garry Bevan

(This site is now posted on the Cenderawasih Bay map)

Pulau Miosauri is the collective name for a group of islands in central western Cendrawasih Bay, formed on and around a massive undersea mountain rising from much deeper water. Running around 34 nautical miles from north to south they are called: Nusambier (this has some extremely pretty sandy satellite islands to the south, Paisin, Numari and Nukup), Maransabadi (the largest), Rumwakon, Iweri, Rouw, Matas and far off to the southeast Kuwom and Rorebo.

Diving Miosauri

During my visits to the Miosauri group I had the opportunity to dive a site I named Rosco’s Ridge in honor of a tender driver who worked on the super yacht I was assisting in Cenderawasih. I was fortunate to dive Rosco’s Ridge twice so I did get a good look at this lovely wall and the surrounding reef structure. The western side of the reef is definitely the place to concentrate your diving.

Rosco’s Ridge

GPS: South 02° 00.100’ : East 134° 41.750’

Info: Very deep wall and reef dive. This dive is reminiscent of the big walls on the islands were shallow reefs extend away from the islands before abruptly dropping into hundreds of meters.

Location: On the west side of the Nusambier group. The entry point preferably would be close to the GPS point on the flat sandy bottom inside the gully created by the islands of Numari and Nukup.
The best dive at Rosco’s Ridge begins on the top of Nukup Island’s wall and progresses south.   Divers should adjust their entry depending on the current flow.

Dive Type: Wall and very steep reef. At the entry GPS point however, between the islets, there is a large sandy patch in a depth of around 10 meters that features several interesting coral bommies.

Depths: 5-50 meters

Corals: Although there is some damage in the shallower areas there are also some very prolific growth, particularly on the edges of the wall down into the first 15 meters.

Marine Life: When we dived Rosco’s Ridge there was not much schooling action close to our entry point, but as the dive progressed we saw increasing numbers of fish, particularly on the wall points were the current was at its strongest. The most interesting area, however, was where the the sand chute interfaces with the wall, the suggested entry GPS point. Here, due to what I believe to be the start of an incoming tide, the numbers of schooling fish increased considerably as the waterway between the islands becomes something of a food trap. On a strong outgoing tide this may well get even better with nutrients being forced up an over the ridge into the shallower water. One of our divers spotted a couple of sharks of indeterminate type. One very friendly turtle was photographed on a coral head. On and over the sand chute we encountered lot of schooling snapper, and, of course, the much more common surgeonfishes.

Garry Bevan is a long time resident of Bali. He has been involved for 20 years in various under and over water capacities, including cruise director with the Peter Hughes Diving/Dancer fleet on the Komodo and Paradise Dancer vessels as well as many other liveaboards and private yachts.
On shore he produces media articles, presentations, movies and is a frequent contributor to this website. He is presently in the middle of a 12 year “battle” to produce dive site guides for Komodo and Alor.  He can occasionally be found in Sanur,Bali fiddling around with dive compressors and playing loud bass guitar with his band, “The Thuds”.