From Bulbapedia, the community-driven Pokémon encyclopedia.
Floe Island (Japanese: こおりしま Ice Island) is the fourth and smallest island in the Sevii Islands archipelago. It is south of Knot Island, and west of Chrono Island.
When the player first arrives at the island and walks outside of the dock building the rival comes up to them and explains to them that they can't fill up their Pokédex without the use of breeding and hatching Eggs, referring to baby Pokémon because they can't be found in the wild.
The town of Four Island is the hometown of Lorelei of the Elite Four. It is here that she was first taught about Pokémon when she was just a young girl. Lorelei still resides in the town. Her house has a large collection of Pokémon dolls she has collected.
Floe Island is also host to a very large Pokémon Day Care run by an elderly couple. For a small fee, they will watch after a Trainer's Pokémon and raise their levels. Unlike the Day Care on Route 5, two Pokémon can be dropped off. Leaving compatible Pokémon at this Day Care will result in a Pokémon Egg being laid.
Next to the Poké Mart, there is a house owned by a man who will put stickers on the Trainer's Cards of Trainers who have accomplished a difficult task, such as defeating the Elite Four, hatching Pokémon Eggs, or completing the Pokédex.
While the Sevii Islands are mostly tropical, there is one exception - a cave on Floe Island. The cave is on the northeast section of the island past a small lake. It is freezing inside the cave, due to the high population of Ice-type Pokémon that live there. For this reason, it is known as Icefall Cave. During Pokémon FireRed and LeafGreen, Team Rocket arrives here; however, with the help of the player, Lorelei and her Lapras, whom she met in the cave during her youth, are able to drive out the villains to their home base on Chrono Island.
To reach this island, a person has to have a Rainbow Pass, instead of the ordinary Tri-Pass.
Locations on Floe Island