Posted on September 24, 2013 | Comments
Ventured out to the “Bridge” to do some exploration dives yesterday, September 21st. The Bridge is an underwater ridge connecting the SE tip of Eleuthera (a.k.a. Lighthouse Point) to Little San Salvador, about 11 miles away. The bridge has depths of 22′ to 75′ across the top of the ridge, and varies in width from about 2 1/2 miles to less than 1/2 mile. The orientation of the bridge is almost East-West, with the water depths on both sides of the bridge reaching 3,000-5,000′ within a mile of the bridge on either side.
Our primary reason for diving the bridge is doing drift dives, as there is a large area of ocean water that moves across the bridge, which is confined by Eleuthera to the West and Little San Salvador to the East, during the times of tidal flow. We have explored the north side of the bridge on the Eleuthera side, where there is a gently sloping bottom moving to deep water.
We have heard stories about the South side of the bridge, where the stories go, has a very defined and steep wall with lots of coral on the “top of the wall”. The only problem is when diving the South side of the Bridge on a rising tide, where the tidal water flow is from North to South has the potential to create a downdraft of notable distinction. In one of the DAN (Diver Alert Network) Alert Diver Online articles, by Neal W. Pollock, Ph.D., he writes “In Dealing with Downdraft currents”,
"My fundamental recommendation is that divers think in advance and be prepared with a continuum of responses from which to choose and, when appropriate, to shift between. The progression of the graded response would be as follows: a mild downdraft could be ignored; a little more strength would prompt horizontal swimming to move out of the affected zone (with minimal or no addition of air to the BCD); even more strength or an uncomfortably large downdraft flow zone would prompt grabbing the wall for stability and, possibly, climbing out."
We elected to minimize the potential risk and dive at slack or near slack as best we could approximate. We dropped into water about 400′ deep just immediately south of the wall, with the wall in sight and proceed to descend to around 70′ and then swim from our position West along the wall. We had a little tidal flow from the North to the South, but was minor and manageable, visibility was 100-150′ with what appeared to be a considerable amount of plankton in the water.
The back side of the wall is a lengthy sand flat area with a depth of 80-100′, with the top of the wall at about 75-80′ where we started and once we crossed the “sand channel” the top of the wall was around 65′. The coral formations are very impressive, with very large species of what are usually seen in small clusters. There is lots of topography along the wall from top to the back side or the actual wall itself. The wall is quite dramatic in the vertical nature with a “lip” of impressive size along the area we explored. Dive one lasted about 35 minutes with a maximum depth of 80′.
For dive two we moved back onto the Bridge itself, to a mound structure we had not dove, with a shallow depth of around 22′ and a maximum depth of 65′. A large series of hills and valleys with lots of varieties of smaller tropical fish, and of course several sharks coming just close enough to verify we were not taking anything off the reef. The current did not really materialize, even thought we are at full moon. Towards the end of dive 2 we were dealing with some wave surge produced by waves of 2-3′ with a period on 8-10 seconds. Dive 2 lasted 58 minutes.
the wind was effectively nonexistent, so for dive 3 we slowly motored around until we could see some interesting structures on the bottom and decided to check them out. We agreed before going in we would limit dive 3 to around 30 minutes, as Dr. Steve had risen early in Spanish Wells, drove down (almost a 2 hour drive) and wanted to return home on the same day. We ended up diving for 34 minutes and getting back to the dock by around 3 pm. Dr. Steve was back at the Gene’s Bay ferry to Spanish Wells before 6:30pm (he stopped at our house to drop me off and have some ice tea).
Great exploration day, a little over 2 hours of actual bottom time and we discovered 2 new dive sites on the Bridge. The south wall on the Bridge, called “Staghorn Reef” is an advanced dive which will require being there when the tide is slack. The “Mound”, called “Roller-Coaster Mound” for all the ups and downs, is a fairly easy dive and would be great for a first drift dive for those who have not done open water drift dives.
Don’t worry about places to explore, we still have about 95% of the Bridge left to explore, so if exploration diving gets you moving come on down we love to do exploration dives. Bring your creative side, when we find a new dive site during exploration dives, the divers get to name the site.