Your trusty boat, the Unsinkable 2 enters from the right and drops Dougal in the water. From there you must swim down and collect each of the five encryption keys in turn and take them to the end-portal. Each time a key is used, the display on the portal will show how many more keys are needed. When all keys have been used, the portal will dissolve and Dougal will be able to access the bomb. This must be collected and returned to the boat before the countdown timer elapses. If that happens, it's well and truly game-over... BOOM!

Successfully returning the bomb to the boat is the goal of each level. Dougal will climb back on board the Unsinkable 2 which will take him off to save the next reef! Any remaining time on the countdown timer will be converted to bonus points before the next level begins.

On each level there are other collectibles to find. Air cylinders and medipacks replenish air and health respectively. Occasionally the player will come across an alien artifact, no doubt dropped accidentally from a passing flying saucer! Collecting one of these is always a gamble. There are a random mixed bag of about 15 different effects this could have, some good but some bad.

You must battle your way from reef to increasingly difficult reef until you eventually reach Dr. Drax’s secret dock. That’s your chance to finish him off for good, but be warned- he’s no pushover!