Kohunlich and Dzibanché are located in between Xpujil (Campeche state) and Bacalar/Chetumal (Quintana Roo state), about an hour drive from either.
No public transport goes to these ruins, so you’ll either need to rent a car, hire a private driver, or take a group tour.
This highly-rated tour, for example, can take you to both Dzibanché and Kohunlich from Bacalar.
In my case, I was staying in Xpujil before heading to Bacalar. And as the managers of my guest house, Hotel Chaac Calakmul, also run a travel agency, I inquired about arranging a private driver who could take me to the ruins and then drop me off in Bacalar.
We ended up settling on a price of $1500 MXN, or about $75 USD. While I didn’t shop around, this price seemed fair considering how the shuttles to Calakmul cost about $500 MXN per person but need at least three passengers.
Considering how there’s no direct transport between Xpujil and Bacalar, hiring a driver also meant I didn’t need to do an extra transfer in Chetumal.
Being a frugal traveler, I’d originally considered finding a colectivo from Xpujil that could take me to the town of Nicolás Bravo, from where I’d try finding a taxi to both ruins. While perhaps a possibility, this would’ve been much more difficult to figure out and I may not have saved that much money anyway.