You might have already seen this - it is a top 20 things we like doing (we have two boys 10 & 13). It might give you some ideas to start with. exunoplures.info
These free activities in Chiang Mai are great for kids; those that still need a bit of help getting around and older kids too. Best of all, each activity is teenager.
Answer 1 of I have booked 5 nights in Chiang Mai with my teens boys and was hoping to use this as a base to Explore the North. Wanted to visit some of the .