Last November, my dive buddy and I were invited by two friends, both experienced boaters, to check out the fields of Purple Hydrocoral, off the South end of the Northern most Island of the Coronados Island chain just over the border in Mexican waters, 17-20 miles from San Diego’s Mission Bay, depending which island you visit.

The fields of Purple Hydrocoral are actually just a few hundred yards South of a site well-known to San Diego dive charters, called “Keyhole,” a large rocky arch which provides a nice, if exciting swim-through for divers during high tide.

The currents in the open ocean waters south of Keyhole can be, however, a bit treacherous so signaling devices, experienced divers and boat captains are a must, and “live drops” over the hydrocoral are preferred to anchoring in case you get caught in the currents because the boat can just pick you up wherever you surface.

Following a 90-minute ride out to the northern-most island, our captain swung the boat around to the southern tip of the island. After checking our gear and signaling devices my buddy and I rolled in accompanied by two other divers. The fourth diver would prove invaluable to us as he was the only one with an X-Scooter: he would find himself literally pulling the rest of us down to the hydrocoral, saving us hundreds of yards of swimming against a formidable current.

An experienced diver in this area, he had given us an excellent detailed pre-dive briefing before we went in: Follow the underwater ridge down and South, to about 90 feet and then across the crevice to the other side, where the purple hydrocoral lay.

First thing we noticed was the beautiful 50-foot visibility up ahead. The second thing we noticed was the spectacular granite wall on our right, dropping away into 100 + feet of water.

The huge granite walls were covered in gorgeous, lush golden and brown gorgonians, some of them 3+ feet across, waving gently in the current. Huge schools of blacksmith fish and señoritas flitted back and forth in front of us as we swam south/southeast, towards the crevice. To our delight, three seals came down to play with us, zooming back and forth in front of us, playfully charging us and then banking away at the last minute.

As we made our way down towards the bottom, it became apparent the large distance we had to cover. The wall seemed to stretch endlessly in front of us, hundreds of yards into the open ocean, towards Middle Ground, the middle island in the chain.

Luckily, the fourth diver, with the scooter, made repeated passes, pulling each of us towards to the fields of hydrocoral near the bottom and depositing us above them, so my dive buddy was able to train her HDV [Sony] video camera on them and capture the rich variety of marine life all around us. Our second time on this site, we established ascent and descent lines attached to a buoy for the non-scooter divers.

The four of us swam slowly around this purple hydrocoral ‘garden’ for a few minutes, filming and admiring its beauty before it was time to head back. We knew we had a long distance to cover and at this depth, we needed to get started.

As soon as we began heading northward towards the boat, we hit the ‘headwind’ or strong, southerly current we had been warned about during the briefing.

It grew stronger the further northward along the wall we swam. A telltale sign was the beautiful lush golden gorgonians attached to the wall, which we had admired on the way over, were bent down, vibrating like a blur in the current. Not a good sign! But, after a good 15-minute swim, with some of us pulling ourselves hand-over-hand along the steep canyon wall to our left, we made it back to the boat unscathed, but only after a good workout.

So, between the breathtaking natural beauty of these islands topside and the gorgeous underwater fields of purple hydrocoral, the trip out is well worth it, but make sure that both boat captain and divers are experienced in strong, open ocean currents before attempting.

Dive Spot At A Glance
Location: Los Coronados Islands, Mexico. 17-20 miles South of San Diego, depending which island you visit.
Lat/Long: 32°25’57.34″N 117°17’40.34″W
Note: When diving from a private boat, bring your passport when entering or exiting Mexican waters. A driver’s license is no longer sufficient under recently changed US Immigration Laws. A passport is likely not required for a dive charter boat. Check with the dive charter operator for details.
Highlights: the beautiful fields of Purple Hydrocoral (Stylaster californicus or Stylaster venustus), steep rocky, underwater cliff faces and rich abundance of other sessile, such as sponges, gold gorgonians. Expect rockfish, surfperch, Mola Molas, blacksmith as well as pelagic marine life associated with the Coronados Islands
Access: Open ocean only; make sure boat captain and all divers are experienced in open ocean diving in strong currents.
Depths: 90 to 120 feet
Visibility: 30-50 feet in Winter, a bit less in summer.
Photography: Excellent for both still and video photography.
Hunting: According to Mexican law, if anyone on the boat is fishing or hunting, everyone must be in possession of a Mexican fishing license. Recommend researching all applicable Mexican fishing laws before making the trip, as they may change without notice. Mexican fishing licenses may be purchased in most San Diego fish/tackle shops. Annual or daily/weekly. Recommend paying a little more for the annual license.
Hazards: Depths below 100 feet and strong, open ocean currents. Recommend carrying standard signaling items: inflatable sausage, horn and/or mirror. US Coast Guard may not respond to emergencies in Mexican waters.