Appendix:Gold and Silver walkthrough/Section 9

Olivine City

The port city of Olivine, sister city to Kanto's Vermilion, is a Trainer's next stop on the way to the Pokémon League.
When you first arrive in the city, your rival stops you near the Gym. He mentions something about the Gym Leader tending to a sick Pokémon in the lighthouse before running off.

Hook the Big One!

On your way into the city, stop by the first house south of the Gym. Speak to the the Fishing Guru and if he can tell how much you enjoy fishing, he will give you the Good Rod. With this, you will finally be able to fish for Pokémon other than Magikarp!

Time for a Trade

North of the lighthouse are two small houses, and the man in the left house is looking to trade. If you have an extra Krabby, this guy will offer to trade you his Voltorb.

Super-Strength

Before heading off to the lighthouse, make sure to stop in the diner to the west of the Poké Center. Speaking to the sailor inside will get you HM04 (Strength), a powerful move that allows a Pokémon to shove large boulders around like toys.

Save the Lighthouse Beacon!

The Olivine Gym Leader is tending to the lighthouse beacon on the sixth floor, a sick Ampharos that would normally use its tail to illuminate the ocean.
Battle your way to the third floor, and take the stairs in the northeast. On the fourth floor, battle past Lass Connie and drop down the hole to the third floor below. You'll be ambushed by Sailor Terrell; defeat him, grab the Ether nearby, and take the stairs back to the fourth floor. Head up the next set of stairs to the fifth floor, and battle Sailor Ernest. Grab the Great Ball lying in the corner, and take the stairs to the sixth floor, where you will meet Jasmine.
Her Ampharos is very sick, and she cannot leave it unattended. She talks about a pharmacy across the ocean in Cianwood City that specializes in a form of unconventional medicine. Jasmine will not return to her post at the Gym until Amphy is better, so get ready for a swim! Teach a Pokémon HM03 (Surf) if you haven't already, and leave west from the city to reach Route 40.

Later...

After defeating the Pokémon League, Trainers will be able to board the S.S. Aqua. This ferry service sails between Johto's Olivine and Kanto's Vermilion. After the initial voyage to Kanto, the ferry sails to Johto every Sunday and Wednesday, and back to Kanto every Monday and Friday. Like the S.S. Anne, there are many Trainers on-board that are looking to battle.

Routes 40 & 41

Route 40 is a small beach that leads off into the ocean. The only notable thing here is available just once a week - Trainers who speak to Monica on Mondays will receive a Sharp Beak, which enhances Flying-type moves when held.

Route 41 is a small portion of Johto's ocean, surrounding the Whirl Islands. When a Trainer first travels the route, the islands are inaccessible, since the Trainer has yet to collect HM06 (Whirlpool) and the Silver Wing. As these two routes form the only ocean in Johto, there are a handful of new rare Pokémon to find. Trainers can surf through the islands however they please, though just south of the islands, the route turns to the west on the way to Cianwood City.

Routes 40 & 41:

Route 40:

Route 41:

Whirl Islands

The Whirl Islands form a small island chain between the mainland and Cianwood City's landmass. Initially inaccessible to Trainers, the islands are protected by a group of violent whirlpools that guard the four islands' entrances.

Later...

Return to the islands after obtaining HM06 (Whirlpool) and the Silver Wing, which allow Trainers to thoroughly explore the islands' cave network. The northeastern island is the only way to reach the deepest caverns under the islands, where an immense, silver-colored Pokémon is said to make its home.

This article is part of Project Walkthroughs, a Bulbapedia project that aims to write comprehensive step-by-step guides on each Pokémon game.