Explore more at ocean.org
Page background

Diving Sponge
Reefs & Gardens

Sponge Garden = cloud sponges growing on rock

Fragile Bioherms

Glass sponge reefs are unlike anything else in the world. These fragile bioherms can reach 14 metres in height and cover a square kilometre, providing an important habitat for the fish that live in them. Until about 25 years ago, people believed that glass sponge reefs had gone extinct during the Jurassic period, but then they were discovered living in very deep water in Hecate Strait in northern British Columbia. During the last 15 years, biologists have discovered several of these ancient glass sponge reefs at locations in Howe Sound where the depths are shallow enough to be safe for divers using compressed air. Expert sport divers can safely get to these reefs, located between 25 to 35 metres in depth. 

Sponge Halkett Pinnacle bioherm, 2009
Sponge bioherm

Documenting Growth

We need to raise awareness of these reefs if there is to be any chance of them being considered for protective management to ensure their future. Vancouver Aquarium divers have been monitoring three areas  of the Defence Island sponge reef, but we can learn more from repeated observations at precisely defined places. For that reason, the Howe Sound team has installed a series of colour-coded stakes on this reef, so locations of photos and videos can be documented over time. We can measure the growth of the reef by comparing shots of the glass sponges adjacent to the stakes through time.

We Need Your Help

We can't be in the water every day, so we are calling on divers to assist us in collecting important visual data on these sponge reefs and sponge gardens. It's a relatively easy task for divers equipped with cameras; simply plan your dive to include swimming around the markers located within the bioherm. Take photographs or videos, which include the markers, and then submit this online to us using the form below. Sponge reefs grow on a base of dead sponge, whereas in sponge gardens the growth is on rock.

diver with sponge Sponge Garden = cloud sponges growing on rock
Defence Island Inshore Bioherm (N.B. this depiction is a view up-slope from the N, looking S). Defence Island Inshore Bioherm (N.B. this depiction is a view up-slope from the N, looking S).

Sponge Diving Tips

There are nine stakes around the outside edge of the Defence Island inshore  sponge reef, plus a series of three stakes at the top of the ridge line of the reef (identified by red stripes) to enable orientation by divers. Another stake with a temperature logger is located at the end of the yellow guide rope, east of the black vee  pipes. Divers should not approach the three central ridge stakes in order to prevent any chance of mechanical damage to the delicate sponges by divers making contact. Instead, divers should swim around the outside of the reef and shoot uphill toward the main body of the reef, always keeping a striped stake within the frame of photos or videos. The idea is to keep fins away from the reef and to shoot in toward the reef, always with a reference stake in the shot. The depth profile for diving this reef is such that a separate dive should be devoted to each set of three stakes (blue-striped vs. black-striped vs. green-striped).

Diving Green–Stripe Stakes

The green-striped stakes along the northwest border of the reef are over 30 metres in depth and widely separated, so they are only recommended as a dive for experts who are already experienced with the overall reef site. A yellow guide rope leads from the rocky ridge anchor site to the vee of black stakes marking the starting point. For the green-striped stakes, swim north from the black stakes, high above the top of the reef, and head down until you see the green striped stakes. Three stripes always designate the centre of the reef, changing to two stripes and then one stripe as you move to the outside of the reef. At the three-striped green stake, turn and orient toward the south to get the reef in view (look south, up toward the red-striped stakes on the top of the ridge) and shoot around the three green-striped stake. Then, move west to the two-striped stake, and then finally to the single-striped stake. After shooting around those stakes, start the ascent over the top of the reef, then surface a bit further south near the boat.

Sponge bioherm

Diving Black-Striped Stakes

The other two sets of stakes can be shot in slightly shorter dives.  For the black striped stakes (toward the east), start from the black V of stakes, head east up the highest ridge (with dead sponge remnants from the 2009/2010 El Nino) and over to the stake with a single black stripe, at the eastern extremity of the reef. Shoot uphill (oriented south) at that stake, then move west (along the down-slope of the northern margin of the reef) to the two-striped stake, and finally to the three-stripe stake. After shooting the northeast face of the reef, orient up high over the reef toward the red-striped stakes, return to the black V of stakes and then use the guide rope to locate the boat anchor site.  

Diving Blue-Striped Stakes

For the blue-striped stakes, proceed just slightly west from the black V stakes, from where the red-striped stakes can be seen, uphill to the north. After shooting around the blue three-striped stake, proceed a short distance west to the two-striped stake, then to the deeper single-striped stake near the southwestern end of the reef. From that last blue-striped stake, ascend a short distance uphill, to the north, to the ridgeline stakes, which should be viewed safely from high above to avoid any chance of damage to the reef. The return circuit to the east will lead again to the black V-shaped stakes and then to the yellow guide rope to the anchor chain for ascent.  Bottom time should allow the same descent and ascent paths for this shallower dive . 


Submit Your Data

Thank you for collecting sponge data for us! Please submit your details below. If you are uploading images you can upload them through our form. If you are submitting video please upload to YouTube or other video hosting service and provide us with the link to view.


Files can be submitted for web posting to fishresearch@vanaqua.org

Photo Gallery Submissions

Please click on photos to see larger. 

Thank you all divers who have submitted photos: Diane Reid, Paul Sim, Adam Taylor, Donna Gibbs.

Thank You To Our Sponsors



Share Your Thoughts

How was your visit? Fill in our comment card and let us know.
Find it here


Donate Now

Your donation supports ocean conservation.

Did You Know?

Did You Know?

97 percent of all animals on Earth are invertebrates. 
Read more