Jabal Akhdar (or Jebel Akhdar) is a peaceful place in the middle of a mountainous range, just 30 km from Nizwa. It's easy to access the mountain. All the same, here are some tips to get there and possible things to do there.
During your trip to Oman, you can easily get to Jabal Akhdar by car from Muscat. You should allow about two hours to drive there and you won't necessarily see any road signs on the road. It's better to ask for the GPS coordinates of the place from locals before you leave.
On the other hand, it's essential to go there in a four-wheel drive vehicle, like a 4x4. Indeed, before you reach the Jabal Akhdar road, you'll have to stop at a checkpoint. Only cross-country, 4-wheel drive vehicles are authorised to continue their route. The last stretch is relatively steep, which is why this type of vehicle is compulsory.
My little tip: leave early in the morning, around 4 a.m. (if you're leaving from Muscat), then you can enjoy the scenery and walks without the excessive heat.
In Oman,Jabal Akhdar is in full development. The Omani government has invested in the infrastructures required to make this place one of the country's tourist attractions.
There, you can find hotels ranging from a simple establishment to a five-star hotel. On the other hand, it's not easy to sleep in a local's home. In effect, as the village was remote for such a long time, the locals aren't yet used to accommodating foreigners for the night. In spite of that, you'll always be warmly welcomed to drink tea and eat halwa (a sugary local speciality with spices).
When you arrive in Jabal Akhdar, you'll notice the dense vegetation. It's the most striking point: in the middle of dry mountains, there's cultivation present, all the same. In May, you'll have the opportunity to stroll amongst rosebushes. You can take numerous walks, especially by following the "aflaj" (irrigation systems).