We found an amazing restaurant in the north end of Koh Rong, accessible either by Kayak, motorbike, or walk. It's called Firefly Guesthouse, Restaurant and Bar. We didn't stay here, but it easily had the best food we found on Koh Rong (and Cambodia!).
What makes this restaurant so good is that the owner used to work as a chef for the Song Sa Private Island resort - a Bora Bora Four Seasons inspired resort that you can see from his restaurant. However, instead of charging through the roof, a meal will cost you only USD$2 - USD$8. Check out the menu below:
If you are planning to stay here, book through WhatsApp or Telegram +855 017 418 567 / +855 010 418 567 and pay in cash on arrival - this will be cheaper for you, and the property owner won't lose cash to booking.com fees. When you book directly, the prices for accommodation are:
Dormitories (1 bed): USD$9
Double room (1 bed, 2ppl): USD$18
Family room (2 beds, 4ppl): USD$25
Kayak (24hrs): USD$ 7
Motorbike (24hrs): USD$12.50 incl. petrol
Mountainbike (24hrs): $10
Getting there is very easy - simply put Firefly Guesthouse, Restaurant and Bar in your Google Maps and follow the path - just make sure to put your maps on satellite mode. You can ride your motorbike the whole way there, take a kayak from Lily's Riverside House, or walk there.
If you are walking or riding there, Google Maps will only take you as far as Prek Svaey Primary School. Make sure you have your map in satellite view, and you can follow the path all the way to Firefly Guest House. For your convenience, see the map below with the path highlighted in red.