Guanaja is one of the Bay Islands of Honduras and is in the Caribbean. It is about 70 kilometres (43 mi) off the north coast of Honduras, and 12 kilometres (7.5 mi) from the island of Roatan. One of the cays off Guanaja, also called Guanaja or Bonacca or Low Cay (or just simply, The Cay), is near the main island, and contains most of the approximately 10,000 people who live in Guanaja.

The densely populated cay has been described as the Venice of Honduras because of the waterways that run through it. The other two main settlements on Guanaja are Mangrove Bight and Savannah Bight. Smaller settlements include East End and North East Bight.

Guanaja was discovered by Christopher Columbus on his fourth voyage in 1502. Notably, this was the first time he came across cacao, which is the core of chocolate. He landed on Soldado Beach on the north side of the island. In later years Cayman Islanders settled in the Bay Islands, which explains the diffusion of Spanish and English language.

Transportation is sparse, and as of 2006, there were only three cars on the island, but by the end of 2011, there were roughly 40. While there is only one road, from Mangrove Bight to Savannah Bight, the most common means of transportation are boats. A channel locally known as "The Canal" allows access from the south to the north side of the island without having to go all the way around. Guanaja is served by the Guanaja Airport (GJA).

It is highly recommended that you hike to the top of the island, where you can clearly see the coast line (on a clear day) as well as getting the full perspective of the entire island and surrounding reef. A beautiful nature hike also available to the waterfall located on the north side of the island.