From Bulbapedia, the community-driven Pokémon encyclopedia.
Honey Island (Japanese: ハニー島 Honey Island) is the first island Ash, Iris and Cilan visited during their travels through the Decolore Islands. It is well known for the sweet honey that some of the Pokémon here produce.
In Danger, Sweet as Honey!, on the island, Ash got invited to partake in an All-You-Can-Eat lottery which turned out to be a scam of Team Rocket. The lottery was an actual trap in an attempt for them to catch Pikachu, and Ash and his friends got taken to the fields of the island and fell into one of Team Rocket's pits. They got out, and before Team Rocket could get away with Pikachu, a swarm of Kakuna evolved into Beedrill which caused the groups to get split into three. After finding each other, Ash and his friends managed to reach the Pokémon Center located on the island and enjoyed the island's famous honey.
It also briefly appeared at the beginning of Cilan and the Case of the Purrloin Witness!. Ash, Iris and Cilan boarded a new boat at the harbor, as they had missed the previous boat that left Honey Island.
Pokémon seen on Honey Island