Flower Garden Banks · United States · Reef
McGrail Bank
The only known reef dominated by blushing star coral
Photo: NURC/UNCW and NOAA/FGBNMS. · Public domain
The deep outlier of the sanctuary, 109 miles (175 km) from land and brought inside the boundary by the 2021 expansion. The top of the bank is at 44 m, so this is not a coral-cap dive: it is the only reef known to be dominated by blushing star coral, Stephanocoenia intersepta, with coral cover as high as 28 percent. There are no mooring buoys here.
Also known as 18 Fathom Bank.
Where it is and how deep
27.9567° N, 93.3167° WApproximate position — the dashed circle shows where the site lies; your operator's briefing has the mooring.
Site maps published elsewhere
The dive
Nothing about McGrail is casual. The shallowest ground is 144 feet (44 m) and the bank falls away to 156 m, which puts even the top of it at or past the edge of recreational diving, and unlike East and West Flower Garden and Stetson it has no mooring buoys installed. Anchoring is not permitted anywhere in the sanctuary either, so there is no fixed line to descend or ascend on.
What is down there is unusual. Large colonies of blushing star coral, Stephanocoenia intersepta, dominate the reef, and no other coral reef is known to be dominated by this species; overall coral cover is as high as 28 percent. Surveys record butterflyfish, roughtongue bass, grouper, snapper, creolefish and wrasse over the reef, along with sandbar sharks.
The deeper portions of the bank hold mesophotic coral communities: black corals, octocorals, fish, sponges, algae and invertebrates in light too dim for the shallow reef builders. None of that is within recreational reach, and neither is the reef above it. The whole bank came inside the sanctuary boundary with the expansion that took effect on March 22, 2021 and protected 14 additional reefs and banks.
Background
The bank was formerly called 18 Fathom Bank and now carries the name of David W. McGrail, a Texas A&M and U.S. Coast Guard oceanographer. It came into the sanctuary with the expansion announced on January 19, 2021 and effective March 22, 2021, which protected 14 additional reefs and banks, adjusted the boundaries of the three original banks, and grew the sanctuary from 56 square miles (145 sq km) to 160 square miles (415 sq km).
Marine life and season
- Groupers
- Pristine corals
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Off-season | Off-season | Fair | Good | Good | Prime | Prime | Prime | Prime | Good | Fair | Off-season |
Season follows Flower Garden Banks: Charter season runs roughly April-October when Gulf seas are calmer; coral spawn a few nights after the August full moon, and winter cold fronts shut most operators down.
Know before you go
- The top of the bank is at 44 m with no mooring line to hold, so this is a decompression dive that has to be planned and supported as one.
- Currents run in different directions and at different speeds at different depths, and can develop or disappear in the middle of a dive.
- Over one hundred miles of water lie between the bank and the nearest medical facility.
Photos from McGrail Bank
NURC/UNCW and NOAA/FGBNMS. · Public domain
NURC/UNCW and NOAA/FGBNMS. · Public domain
NURC/UNCW and NOAA/FGBNMS. · Public domain
Questions divers ask
How deep is McGrail Bank?+
The shallowest point of the bank is 144 feet (44 m) and it descends to 156 m, so there is no recreational profile on it. It also has no mooring buoys, unlike East Flower Garden, West Flower Garden and Stetson banks.
What makes McGrail Bank unusual?+
It is the only coral reef known to be dominated by blushing star coral, Stephanocoenia intersepta, with coral cover as high as 28 percent, and it was added to the sanctuary in the 2021 expansion.
Sources
- McGrail Bank — NOAA Flower Garden Banks National Marine Sanctuary
- Sanctuary Banks — NOAA Flower Garden Banks National Marine Sanctuary
- Mooring Buoys — NOAA Flower Garden Banks National Marine Sanctuary
- Trip Preparation — NOAA Flower Garden Banks National Marine Sanctuary
- Flower Garden Banks National Marine Sanctuary — Wikipedia
Photo credits
- Large boulder coral colony on McGrail Bank's reef, reef fish schooling overhead by NURC/UNCW and NOAA/FGBNMS., Public domain, via Wikimedia Commons
- A dark encrusting sponge dominating a reef outcrop on McGrail Bank by NURC/UNCW and NOAA/FGBNMS., Public domain, via Wikimedia Commons
- Bright orange elephant ear sponge growing on the reef at McGrail Bank by NURC/UNCW and NOAA/FGBNMS., Public domain, via Wikimedia Commons
- Pink barrel sponge on the reef at McGrail Bank by NURC/UNCW and NOAA/FGBNMS., Public domain, via Wikimedia Commons
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