There are more than one lantern in Poptropica. The one that most people will encounter is on Cryptids Island, but there is also one in the Haunted House maxi-game in the Poptropica Store.
Haunted House
Go to the bedroom, and synchronize the clocks so that they both strike midnight at the same time. The lantern, one of the five treasures, will appear in the fireplace.
Cryptids Island
In the Himalayas, climb the mountain and enter the monastery. The head monk will not let you have the Yeti scalp, but he gives you a lantern to light your way. You need the lantern (and the matches from the pub at Loch Ness) to light your way in the dark forests of New Jersey.
You will get it from the fire then go to the kerosene and fill the lantern up.
You get the lantern and light it with the kerosene.
When you get the lantern go down stairs and find a barrel and click it. Then the lantern will light up.
The jack'o'lantern is a costume, previously available in the Poptropica Store.
To light the lantern in the haunted house you have to go to the floor you came in on and click on the kerosene barrel.
You go to the ghost cat and click on him.
You find the Karosine by the stairs in the cellar.
matches loch ness lantern himilaya
There is a barrel of kerosene under the stairs in the basement (where you entered). Click on it to fill the lantern.
The monk from the Himalayan temple gives it to you.
It is red... like your average lantern.... you have to play with the clocks to get it though... look up "Haunted House Poptropica Walk-through if you want to know how to beat the clocks.
go to the place with the boiler. by the stairs there will be a barrel that says kerosene. click on it and your lantern has fuel.