I'm coming to Kota Kinabulu with an elderly lady (who used to live there and speaks Malay/has lots of friends) - If I want to see some cool forest animals, or at least try, what is the best place/way to do that? Hire a van/driver and go? Ask when I get there? She is mobile but....she's 89!
I went to Kota Kinabalu a few years back with my family – including my (at the time) 83 year old grandmother and 80 year old pop.
We went to the Nature Reserve at Shangri-La's Rasa Ria Resort (fancy, I know). It was a steep and very warm hike up a lot of stairs to the feeding platform, but nan managed to battle through it pretty well. Afterwards the cafe was nice to chill out and have a bite to eat/cold drink before heading on the bus back to where we were staying.
I took a day trip (flight from Sabah to Sandakan) to see the Sepilok Rehabilitation centre. It was quite a pricey trip, and we only saw one or two organutans. I'd suggest skipping that if you're short on budget.
Again, this was a few years back, but my best suggestion would be to head to the Shangri La (You don't have to stay there, just check pricing for the day trip).
Enjoy the trip! 3 months ago