To find the third bot in the Bubbling Under level of Astro Bot, follow these steps:

1. Locate the Tower: After entering the main area of the stage, you will see a massive bubble dome to your right surrounded by stone columns and with three giant spiky balls circling it. This helps you understand the layout of the stage.

2. Identify the Sunken Ship: Swim up and look for a sunken ship. Above the ship, you’ll see a bridge with multiple geysers. The first bot in need of rescuing is stuck in one of these geysers, but this is not the third bot.

3. Find the Wooden Platform: The third bot you need to rescue is standing on a wooden platform on the surface of the water. This platform is located in the corner of the stage, to the right of the massive starfish.

4. Rescue the Bot: Once you reach the wooden platform, a UFO Bot will snag the third bot. To rescue it, approach from below and dash up and out of the water directly into the UFO. Make sure you line up your shot, and you should get it in a few attempts.

Detailed Steps:
– Swim to the Right Side: From the main area, swim towards the right side where you can see the wooden platform.
– Locate the Starfish: The wooden platform is near the massive starfish.
– Approach from Below: Swim beneath the water and approach the wooden platform.
– Dash Up: Use your penguin power or any other boost to dash up and out of the water directly into the UFO.
– Rescue the Bot: Ensure you line up your shot correctly to rescue the bot.

By following these steps, you will be able to find and rescue the third bot in the Bubbling Under level of Astro Bot.