The presence of the sandy shoal that extends from the northeastern tip of Treasure Cay Beach to Whale Cay forces most deep-draft vessels attempting an east-west transit of this area to detour offshore (Whale Cay Passage). However, in recent years it has become possible to bypass this route by following the so-called "Don't Rock Passage," as shown in the accompanying chart and photo.
We have followed this route several times since the summer of 2001, and have found at least 4 feet at low tide at its most shallow point (a shoal near the eastern aspect of the passage), and over 6 feet at high tide. Heading east toward Marsh Harbour, the passage begins at a point roughly 50 yards north of the Sand Bank Cays (26-41.75N/ 077-15.63W), heading ESE to a point roughly 50 yards NE of Don't Rock (26-41.13’N/077-14.71'W), a distance of a little over 1 nm. This is easy site navigation; I provide the GPS waypoints, allowing the navigator to insert them into a route plan.
There are a few important qualifications: the principal advantage of this route is it shorter transit time and distance. It really isn't a viable alternative when the Whale Cay Passage is closed by rough seas, because the same forces typically cause breaking waves in this area as well. I have flown over this passage twice during a rage, at an altitude of about 1000', and I can verify that the shoals break impressively. The risk here is two-fold: there is danger to the boat's running gear/lower unit should it be caught in a deep trough, i.e. "grounding out," and there is also the possibility of the boat being swamped.
I suggest you proceed with caution the first time you try this. The shoal near Don't Rock, especially at low tide, looks "scary shallow." We came through the passage in June of 2015 an hour before high tide, we had at least six feet the entire way. We saw several deep draft sailboats making the passage as well. The diagram below still appears to be accurate. The Sand Bank Cays and Don't Rock make convnenient and useful landwarks.
The Don't Rock Passage greatly simplifies the run between Green Turtle Cay (Settlement Creek-New Plymouth or White Sound-Bluff House) and areas of Abaco to the SE of the Treasure Cay-Whale Cay shoal, such as Guana Cay.
From Guana Cay's Settlement Harbour, steer 280M to Don't Rock, a distance of about 7 nm. Don't Rock is visible after running about 3 nm, it looks like a dark "spot." Run the passage as described, a little over 1 nm, then steer 320M for about 5.5 nm, taking care to remain SW of the shoal that extends from GTC. Then head north for about a mile into Settlement Creek or White Sound, a total distance of roughly 14.5 nm.
From GTC, run south from either Settlement Creek or White Sound, taking care to idle through the anchorage, as well as avoiding the shoal on the SW aspect of GTC, then run 140M to the Sand Bank Cays. Transit the Don't Rock Passage, then run 100M into Guana's Settlement Harbour.
Both runs, as well as the Don't Rock Passage, can easily be accomplished by site navigation and a compass; no GPS is required. Please consult Dodge for detailed charts of the approaches to the above harbours. In May 2009 Abaco Forum member Pellucid explored the area and generated the following diagram. Measurements were obtained with his depthsounder, and converted to MLW. Pellucid writes:
"The picture shows my estimate of the 3 foot contour, based NOT ON HYDROGRAPHY but on paying attention to my depth finder and the color of the water. The blue line is the recommended course. Many boaters go around the north end of Don't Rock. It has shallowed a good bit from what I remember a few years ago. Still 5ft. MLW but there is deeper water on the south side. The sandbar to the E-NE of the Sandbank Cays has grown a bit. It's easily seen and avoided; note the slight dogleg in the recommended course. The blue line should give you an honest 4ft. MLW all the way through and maybe a tad more."