Recommended Team: Sonic (Leader) & Tails (Partner)
Ocean Base Act 1 begins above water, with a series of platforms and grind rails. Maintain your speed and use Tails' flight to reach higher ledges or bypass small gaps. Soon, you'll encounter the first underwater section. When submerged, your movement speed is significantly reduced, and you have an oxygen meter that slowly depletes. Look for air bubbles released by specific enemies or from vents to replenish your oxygen. If your oxygen runs out, you'll start losing rings rapidly.
Tails' flight can be used underwater to move faster and ascend quickly. There are several destructible blocks underwater that hide pathways or air bubbles; use a Spin Dash to break them. Look for a hidden Special Spring behind a series of underwater pipes; you'll need to navigate a small maze to reach it. The act alternates between above-water and underwater sections, requiring you to adapt your strategy. The goal ring is usually found on a platform above water.