Drift around the first turn, and try to charge a Mini-Turbo. If you pick a proper angle, you should have one ready by the time you reach the wooden ramp. Release the drift for a burst of speed, then grab a coin as you race across the planks.
As you approach the dash panel, aim for the coin to the right. Approach the coin from a slight angle, but steer clear of the support beams below the large sign. Remember to hop from the edge of the dash panel; this provides a small burst of speed when you hit the water. While in the air, push up on the Circle Pad to tilt your kart downward. When you reach the maximum angle, release the Circle Pad.
When you hit the water at this angle, your kart takes much longer to reach the ocean floor. This helps maintain your speed and allows you to float over a large rock that would otherwise block your path.
If you’ve managed to clear the rock, you should touch down on a slight incline. Veer toward the narrow ledge to the right, and hop from the top of the bump to gain a small boost. There’s a large chasm to the right, so use caution as you drive along the ledge.
The ledge isn’t that long, but the shortcut can shave several seconds off your completion time. As you drop down from the ledge’s end, avoid the nearby Clampy. Follow a smooth racing line down the center of the path, but look for a chance to grab a coin from a freshly opened Clampy.
When you exit the water, head straight down the wide path as it curves through the center of the cavern. Grab one of the coins ahead of you, then hop from the ramp at the path’s end. Once again, tilt your kart toward the water, then release the Circle Pad before you splash down.
Dodge the Sidesteppers along the floor, then continue across the dash panels to return to dry land. Remember to hop just as you surface—the extra boost of speed is a big help in the final stretch!
Drift into the final turn, then use a Mushroom to cut across the strip of grass. As the boost ends, release your drift to speed through the end of the lap.
Tactics for Laps 2 and 3
Use the same basic tactics for the remaining laps. Focus on clean transitions from dry land to water, and adjust your racing line to snag any conveniently located coins.