Hazelmere's island is the name given to an island where Hazelmere the gnome lives. His house is on the southern end of the easternmost island in this small chain. The gnome can be found on the top floor of his house, unless you have passed a certain point in While Guthix Sleeps.
There are several Jungle spiders that reside in the small chain.
One can use the fairy ring code CLS for quick transportation to and from the island. The fairy ring is located just behind Hazelmere's house.
Upon completion of While Guthix Sleeps during which Hazelmere died while fighting against Lucien, players given this clue were unable to complete it. After some time, Jagex fixed the bug by changing the clue so that it directs the player to speak to Brimstail instead. As a result, Hazelmere is no longer involved in Treasure Trails for players who have completed While Guthix Sleeps.