By car: As of July 2009, highway 307 has been expanded so that there are two lanes on each side for traffic. There was still a sections where the highway has not been completed but it was in good driving condition. There were no tolls to pay. The exit for the city of Bacalar is on the left. The scenery is through the Sian Kaan Biosphere for part of the trip. The driving time from Cancun is 5 hours. Well worth the drive. By bus: From Cancun, via Playa del Carmen and Tulum, go in ADO terminal and buy an ADO (more comfortable with toilet and more expensive expect you don't buy an advance ticket) or MAYAB (It is an old bus without toilet and it is the cheapest around MXN 200, ) bus ticket. There are a lot of buses leaving every half hour more or less, so you just need to make sure with which bus you like to travel. BY Colectivo: You can also take a Colectivo/Kombi, which are departing from Tulum very close to the bus terminal from the main road. Find the one heading to Felipe Carillo Puerto (60MXN per person). Let the driver know that you are heading to Bacaral and he will drop you off at the right place, so you don't have to search for the specific Collectivo station (direction Chetumal). The trip from Felipe Carillo Puerto to Bacalar will be 65MXN per person (prices as of January 2017). You will be dropped in Bacalar on the main street, opposite the gas station.
On foot or bicycle would be very doable if you are staying in the city of Bacalar, as well as taxis, which are not expensive.
The water of Lagoon Bacalar is among the most pale and gem like blue that could possibly exist. The main attraction of travelling to this area is the 7 colours Lagoon, whose beauty could easily induce one to sit and read for a few days without regret. The Lagoon (fresh water) is somewhat shallow at the shores, except where there are sinkholes commonly known as cenotes. It is well seen by kayak or sailboat. The sand when disturbed smells strongly of minerals or sulfur, though sitting by the lagoon or even being on the water certainly carried no odor whatsoever. The Fortress de San Felipe Bacalar, in the center of town, represents one of the bastions used by the Maya before they were overrun by the Spanish, it has a small but modern museum inside, if you are in town it´s worthwhile visiting. On Sunday night, there may be music and dancing in the city square.
Active Nature Bacalar  offers guided kayak/canoe trips, bicycle tours and jungle walks to explore the beautiful lake and its surroundings. They are located 5 km north of Bacalar at Villas Ecotucan which is also a really nice place to stay.
Ramón Aguayo is the certified scuba instructor in town, if you´d like to get certified. Ask for him at the front desk of Villas Bakalar or at the chinese house on the costera. Sailing boat rentals or instructor, aswell as boat excursions are also available.
The mayan ruins nearby that are worthwhile visiting are Chacchoben, Dzibanché and Kohunlich. They don´t have alot of people and the jungle surroundings are magnificent. Contact the front desk of Villas bakalar for birdwatching among jungles and ruins.
Horse-back riding in the rodeo or on trails to Lake Bacalar is available at Num Ka'an Ranch about 10 minutes drive south of Bacalar on Highway 307.
To learn more about Bacalar and what to do, where to buy stuff, where to eat, where to stay, what is going on around town and what has been happening, as well as articles about the fort and danzon, visit the Bacalar Mosaico web site at 
Los Aluxes has a nice little bar with swings instead of stools. Though the closing hours are early (see above)
There are numerous hotels along the Western coast of the lake. Amigo's B&B is nice. Casita Carolina also appears very nice and has a great beach.
5 km north of the town you will find Villas Ecotucan,a little oasis with lovely cabanas and a campground with beach and a lot of activities.
There is a new campsite for backpackers in town "Yaxche-Centro" on Avenida 9, between Calle 22 and Calle 24. This is right in the center of town on the same block as the church and just round the corner (less than 5 mins walk) from the only taxi rank in town. Cels 983 104 3207 or 983 102 0523. This is large and comfortable site with big trees and plenty of shade. There are showers, toilets and a shared kitchen with fridge under the central palapa.
Three blocks walking distance from the Fort is the recently opened Las Villas Bakalar  , the suites are comfortable, styish and big and have air conditioning and internet. The pool is not enormous but has a nice view of the lagoon aswell.
If you decide to stay on the campsite, you don't even need your own tent - you can hire it. There are few campsites in Bacalar ranging from 50 to about 110 MXN per person per night. Some places who offer bungalows or cabins also have an option to set up a tent on their lawn and use amenities. Some of them are easily findable via google, but you can also stroll around the town to look for a good option for you.