Sonic Advance 3
Ocean Base (オーシャンベース Ōshanbēsu?) is the third Zone in Sonic Advance 3. It is an secret base located on the seabed and one of the parts of the earth that Dr. Eggman created when he broke the planet apart with Chaos Control.
The Zone features polluted water and waterfalls that work similarly to the sand falls of Sandopolis Zone that Sonic and his friends can repeatedly jump to climb up the waterfall to get to higher areas.
Other obstacles include giant crushers (some of which will sprout spikes a short while after you land upon them) and spike pits. Features here include giant fan propellers that slowly rise as the player jump upon them (similar in appearance to a smaller feature in Sky Canyon of Sonic Advance 2) conveyor belts and rails that sometimes offer an alternative path to underwater routes.
The boss of this zone is called the Egg Foot, which is similar to the Egg Frog of Egg Utopia in Sonic Advance 2, only this machine has much more powerful legs and there are no gravity changes. The battle begins with Dr. Eggman and Gemerl jumping down from a height beside the chosen character and his/her partner. Eggman will laugh, and the battle will begin.
Eggman has two attacks as this boss: The first is to jump high into the air and stay there, and then to move left and right across the arena, slowly at first, but faster with every hit. When he does this, all that will be visible of the machine are its legs. You must follow Eggman around and stay between Egg Foot's legs. When Eggman stops hovering and comes back down, if you are between the legs, jump up and hit him.
In his second attack he will jump up, as normal, but keep a good eye on the bottom of Egg Foot's legs: there are two energy generators, each inside a "foot" on the bottom of each leg. Just before Eggman comes down, he will turn the "feet" in, stopping you from staying beneath him to strike him. Quickly spin dash away and be prepared to jump as the generators in the "feet" send out a surprise energy attack down both sides of the ground of the arena ( very much like the original Egg Frog's energy attack). If however, you do lose your rings, make the most of it and hit Eggman back.