Every time I am in Ubud I visit the monkey forest - I see something different every time I go. I go there for the peace and to watch the antics of the monkeys. There are heaps of ancient banyan trees with their hanging aerial roots - stunning. The trees are hundreds of years old and so tall that only dappled light makes it through the canopy, so it is a nice place to cool down after the midday sun. It's eerily quiet most of the time, which I also love. If there is any noise, it sounds muffled - weird acoustics which adds to the atmosphere.
The first time I visited the monkey forest in the 1980s, it was a well used road through the forest and that was pretty much it. Often you'd go there and there would be no monkeys to be seen. They have done a great job creating a park with paths, retaining walls and sign-posting. Keepers/caretakers/guides - whatever their title, feed the monkeys and advise tourists how to behave. Every now and then you might hear a muffled scream in the distance - someone has had their sunnies pinched or gained an unwelcome passenger!
There is an ancient mossy temple down the steps towards the river in the gloom and a bigger temple up the steps towards the rear of the forest - both worth a look. The temple gates are usually locked, but you can still see into the courtyard and watch the monkeys get up to mischief. Further south you will come across a row of market stalls along the path leading to the road to Nyuh Kuning, along which you will find Laka Leke (sister restaurant to Cafe Wayan), Chilli Cafe, Saren Indah Hotel, three of the Alam Indah properties, and a few villas.
As you walk through the monkey forest, you will come to a central area with a small rock pool. If the adolescent monkeys are playing in the rock pool, you are in for a treat (see my video clip below). They are hilarious, playing chasey, dive bombing each other off a tree branch, etc.
One time I went when it was a bit cooler, I watched them tiptoe through the water to get to fruit, as if it was icy cold. Very funny.
Another time I was sitting on a retaining wall watching a mother monkey with her gorgeous little baby when another monkey snuck up on me from behind and climbed up onto my shoulder. I stood up and started walking (as instructed by one of the rangers) and it climbed back down - no drama, other than my quaking knees! An American couple came up to me and said I was really brave to let a monkey climb on me, as if I had a choice in the matter or encouraged it! The little critter ambushed me!
If you sit and watch for long enough, you can work out the pecking order of the pack. Fascinating. If the head monkey gives the order to go - they're off, scattering into the trees.
I saw a mother monkey with a dead baby once, cradling it in her arms, trying to get some response from it. It was so sad. You could see her heartbreak. There was no way she was letting her baby go without a fight. Again, fascinating to watch.
Just keep in mind that you are the intruder in their habitat and give the monkeys some space and respect. I personally have never seen them be aggressive, but I can imagine they would retaliate if teased or thwarted, so just use your common sense - we are talking about wild animals here. I have been witness to a few monkey spousal/familial spats - we are not that far removed from the animal kingdom after all.