Wat Umong is a beautiful temple and meditation complex, famous for its natural setting, large stupa, and underground tunnels (which you can enter and photograph). The complex was built over 700 years ago, and is a forest retreat for its many monks. On trees inside are hung Buddhist proverbs and wise thoughts, and there is a hall with Buddhist artwork.
You can also wander down to an island in the middle of a lake within the complex, where you can feed fish, terrapins, and birds.
On Sundays, there are English speaking monks with whom you can converse about Buddhism and life.
The road to this temple links the CMU university with the Suthep/Pong Noi area. This is a tranquil area, but has many picturesque cafes and restaurants. And at night there are even some modern bars and barbecues which you might find a lot of fun!
Please dress appropriately, as this is a temple.
Wat Umong is on Soi 4 Wat Umong. You can either come from the old city Suan Dok Gate (West Gate), and drive all the way down Suthep Road. Soon after you cross the Canal Road, you will see the CMU university on your right, and the entrance to Soi 4 Wat Umong on your left (just after the 7-11). Turn left into that road and follow it until you reach the temple.
Alternatively, you can get to Suthep road via the Canal Road, which is part of the ring road around the city.