The Cave of Mount Otemanu is a hiking route which climbs the northeastern side of the mountain through brush, meadows, and steep climbs to visit a massive cave with nesting seabirds and outstanding views.  Difficulties encountered on the hike include arranging for a hiking guide, avoiding hiking during times of rainy weather (because the trail will become muddy, slippery, and dangerous), dealing with heat and humidity, watching out for rockfall while passing along the base of cliffs, using caution when scrambling on the cliffs outside the cave entrance, and being careful not to disturb the nesting seabirds inside the cave.  Route maps are not provided because we recommend hiring a local guide when doing this hike.  GPS coordinates for the hike starting point are 16° 29.759'S, 151° 43.474'W.
The day after doing our summit hike of Mount Pahia and Mount Ohue, we headed over to the eastern side of Bora Bora for another day of hiking.  This hike would be to the Cave of Mount Otemanu (also known as Anau Cave, the Sacred Cave of Anau, or Te Ana Opea cave).  Doing extensive research at home seemed to reveal that this is the second-best hike on Bora Bora.  The cave is fairly well-known due to the fact that Mount Otemanu is such a distinct mountain and one of the most photographed features of Bora Bora. But seeing the Cave of Mount Otemanu up-close is usually only reserved for people who are on helicopter tours.  One of the special aspects of the cave is that it is home to a colony of Wedge-tailed Shearwaters who return each year for nesting.  These dark-morphed seabirds have dug out small tunnels and burrows within dim areas of the cave in order to raise their young.  Adult birds will usually enter into a previously-used cave burrow in the month of September to begin the 52 to 55-day period of incubating a single white egg (which can measure up to 2.7 inches long and 1.7 inches wide).  Once hatched, the chick period will last 100-115 days, during which the male and female will catch food and bring it back (sometimes by taking turns, sometimes by going together).  After that, the young seabird will reach the fledging stage and begin its independence.  Wedge-tailed Shearwaters are noted for making a wailing sound after dark which sounds somewhat similar to a crying child, which has contributed to island folklore.  It certainly would be eerie to backpack up to the cave and sleep outside of it, only to be awoken by sounds of wailing in the middle of the night.  I'm providing this information on the colony of Wedge-tailed Shearwaters who inhabit the cave in order to encourage all visitors to tread lightly and quietly while inside the cave.  Making loud sounds such as yelling to create an echo in the cave or shining bright flashlights into burrows could frighten the birds.  And trampling around the cave interior carelessly could cause burrows to collapse and bury parents with an egg or chick.  While the seabirds are usually nesting and raising their young from August to March, adult birds may arrive in June to begin cleaning out or digging new burrows and to reestablish pair bonds.  So the risk of disrupting seabird nesting is a concern nearly year-round.

The hiking route to reach the cave can kind of be divided into three sections -- (1) the parking area to the colorful rock wall, (2) the colorful rock wall to the cliff face gully, and (3) the cliff face gully to the cave entrance.  After finding a parking spot for the day on the coastal road, our group began the first section by hiking steeply up an unnamed side road which is located adjacent to the canal of Vairou Bay.  The side road is about 1/10 of a mile long and contains residences all along the south side.  This was the easy part except for the fact that some vicious dogs snapped at us on the way up.  At the end of this road, it is necessary to cross over private property in order to officially begin the hike.  Thus, having a hiking guide with us enabled us to not worry about trespassing or dealing with upset local landowners.  The true hiking portion of the route begins by turning left and following a faint trail into the brush and trees.  After a short while, the trail emerges from the brush and enters an area of pretty meadows.  Unlike the Mount Pahia hike, the hike to the Cave of Mount Otemanu has a lot of sun exposure.  I wasn't really expecting that, so I was glad to once again have gotten an early start.  Being that the route is more wide open, that also means that there are continuous great views.  There are views looking up the mountain toward the cave and summit of Mount Otemanu, and views looking back toward the Anau Ridges, Anau village, the beautiful lagoon, overwater bungalows, and nearby islands of Tahaa and Raiatea.  In order to fully appreciate the views, of course, the hike must be done on a relatively clear day.  The first section of the hike was completed when we reached the base of the colorful rock wall.  From a distance, this area looked like a large pinnacle.  But the trail wrapped around the base of it and followed along the right side, which turned out to be a lengthy high rock wall.  The rock wall has various layers and veins of rock which are quite colorful.  This was the single moment on our trip which reminded me of hiking in Death Valley back home.  Past the rock wall, there was some steep climbing through the jungle which led up to the Mount Otemanu cliff face.  During this portion of the hike, there is definitely rockfall danger from above.  The trail essentially follows along the base of the cliff until it weaves slightly away from it and then enters directly into a gully which must be climbed.  This is the transition from the second section of the hike into the third section.  During rainy weather, it would be nearly impossible to safely climb through this area.  From this point to the end of the trail at the cave entrance, there are nearly continuous steep rope climbs which must be carried out.  The steep rock gully (or streambed) changes into a ground surface that is more sandy and soft, but the assistance ropes continue up the mountain.  This third and final section of the hike is also the most spectacular.  The views are intimidating looking straight up toward the impenetrable summit of Mount Otemanu (elevation 2,385 feet).  In addition to the peak, the sheer cliffs dropping down on both sides are impressive and really make a hiker feel small.  The grand finale of the hike is now reached, which is the Cave of Mount Otemanu.  The cave is both high and deep inside, and quite interesting to check out.  We spent over an hour exploring the interior, peeking at nesting seabirds hidden within burrows, scrambling outside of the entrance area on both sides, and enjoying the views.  It turned out to be a great hike and we were really glad to have included it on our itinerary.  My favorite part was quietly observing the Wedge-tailed Shearwaters.  The Cave of Mount Otemanu was our last major hike on Bora Bora but we also did a smaller one to the "Tree of Life" Banyan tree.  So I will include photographs of that along with a few other bonus ones within the full set of photographs below.  Also, a special thank you to Stephan Duplan of Bora Bora Photo & Video (who does wedding, honeymoon, and underwater photography) for helping to arrange our guide and sending him with a professional camera which took several of our included photographs.  Our hike took place on September 14, 2016.
Many more photographs taken during our visit are available for viewing for this destination.  To see all of them, choose one of the two options presented below.  The two options are Slideshow viewing and Trip Report viewing.  The Slideshow option allows for viewing larger images with an autoplay option and a full screen option (available on most browsers).  This option works very well for large computer screens and tablets.  The Trip Report option allows for viewing smaller pictures in a standard scroll-down format and enlarging of any panoramic photos taken during our visit.  Click on the option of your choice to view all of our photos from this destination.  The Slideshow format opens in a new browser window and the Trip Report format uses the same browser window for viewing.