Once on Moorea and at Vaiare, you will notice two busses waiting for passengers. Bus schedules always correspond with the ferry schedules on Moorea. You want the bus heading north. Get on the bus ($3) and follow it to the Opunoho Bay. Ask the driver to drop you off at the road to Belvedere.
This route will take you to the saddle between Tohiea and Mouaroa and is about the highest point you can get on those two peaks without some extreme climbing.
From Opunoho Bay, walk up the road up the Opunoho Valley and towards Belvedere and Marae Titiroa. Turn right just before the agricultural college and just after the 4wd road that heads to Cooks Bay. Note: You can also do this route from Cooks Bay by following the steep 4wd road from the Paopao Valley and over over the saddle behind Rotui.
A sign points the way to "Vue de Roto Nui et du Marae". If in doubt, inquire locally, as the locals all know where the trail is. You will reach a pig farm after following this road a short distance, and this is where the actual trail starts. The reports I read said, the trail is marked with red markers on the trees, but most seemed to be yellow, at least in November 2005.
The trail heads west and then south, crossing a creek and then a river. There are some nice sections of rainforest along the way. The trail then follows the river, crossing it several times (watch out in the rainy season!). The trail is rather muddy and slippery through the forest before it begins to climb more steeply.
Watch for trail markers (flagging tape and yellow or red spots on the trees) as it is easy to lose the trail in several sections. The final section of the trail is very steep and you must cling to vines, branches, and roots to get all the way up. If it is raining, it is not a good idea to do this section.
If the weather is clear, you should have some really spectacular views from the pass. There used to be three coconut trees at the pass, and hence the name of Three Coconuts, but two of these were blown down during a cyclone in the 1980’s. Obviously, the pass is a bad place to be during a cyclone.
A good pair of boots and at least 3-liters of water are needed.
Note: Due to rain, I didn't make the fina section to the pass, but did get fairly close. If you have completed the final leg of the journey, feel free to make any comments.