@DelacoursLangur indeed! I was very happy after seeing these as well, what an amazing species!
@FunkyGibbon if you're ever in the area again you definitely should! I had all but given up on seeing them myself and was feeling very hopeless while returning back, until the friend with whom I visited Vietnam suddenly spotted these in the distance. I'm sorry to hear you missed them!
Either way a return visit should never hurt though, what an absolutely magical location.
@FunkyGibbon yep, I think that's the only way to see them unless you drag along a spotting scope, then it might be possible to see them distantly from the side but I'd still expect the odds to be lower of seeing them that way. I've heard that you do need a bit of luck but that they're also not completely unreliable - from other people's experiences I think a 50/50 chance of seeing them is probably fairly close to the truth.
The boats go straight forward between two reed beds for a while and then come across a T-junction, but where normally the people steering the boats go to the right they'll go to the left if you ask them to do that instead. My friend and some other EPRC volunteers said this was usually a more reliable area to see the langurs, and often they'd come a lot closer as well because of less boat 'traffic' (even down to the water surface to drink, which is how my friend saw them a few weeks prior to my visit). As visible on this picture I only got distant views and it seems like both Maguari and Chlidonias got much closer pictures, so I don't know if the left half of the reserve is definitively better than the right half.
Ultimately it all comes down to random odds of whether or not the langurs are on the visible side of the cliff or not, though... And even though the people steering the boats will point out the monkeys if they see them they can't pay attention to everything so it helps to scan the cliffs yourself as well - as mentioned above my friend saw these before the boat driver did.
What time of day did y'all visit the reserve (@Vision and @FunkyGibbon)? I feel like early morning or very late afternoon would be your best chances to see them in the open, because while the langurs could be seen at any time of day there is more likelihood of them being hidden within the forest patches during the day (i.e. on the tops/interiors of the outcrops and out of view of the boats).
