- Clear Gem - Destroy all 92 crates.
This is the first water level in the games from Crash Bandicoot N. Sane Trilogy collection. Moving under water is not hard (it is certainly much easier than using a jet pack in Crash Bandicoot 2) but you need patience and precision if you don't want Crash to die by an accident or you don't want to miss none of almost 100 crates.
Start swimming right and from the beginning of the level you should try to find and destroy crates that are placed in various places on the bottom. A shark swims on the right side. Use the fact that he doesn't move vertically and carefully swim below or above him (if you want to take a risk you can eliminate him by using the Spin attack). You should also be careful when you swim close to mines. In default, they are only in one place but they can lean left or right when you get closer to them.
Another crates are behind plants that are presented in the picture. Other crates are also found in similar places. It is very important to check entire area before you move to another section of the ocean.
Soon, you swim near your first fish that regularly keeps changing its volume and when it happens it ejects spikes from its body. Eliminate those creatures when their volume is small (the Spin attack can be used while swimming) or you can completely avoid them.
You reach a big round tank after you unlock a checkpoint. Notice a rotating platform with electric discharges. Wait until you can safely swim into the tank and then use its lower hole.
Keep swimming down but watch out for an aggressive fish that are sticking out. You can avoid them by swimming down and making slalom or attack them and eliminate when they are sticking out slightly. When you reach the bottom you can destroy crates and then start swimming towards the left small tunnel. While you are swimming you can destroy the lower crates that, again, can be hard to notice.
Keep swimming left and when you unlock a checkpoint you can swim inside a new construction (the picture above). Here, you must go down but you absolutely must stop near side ledges because there are a few crates on each one of them. In addition to that the highest upper ledge (the one closest to the starting place) has one, completely hidden, crate that you can easily miss (this place is marked in the picture). The tunnel has 8 crates in total that must be destroyed.
Swim into a metal construction and interact with something similar to a submarine that will help you in your journey (sadly, not throughout the entire level). It has an unlimited number of torpedoes that can be used for destroying crates and to eliminate enemy fish. However, the most interesting use of the torpedoes is the ability to destroy red coral reef (an example is presented in the picture above). Each red object like that hides a new crate.
Keep going right and destroy all interactive objects by using torpedoes. Near the end you can use one torpedo to destroy a mine. When you get closer to a small tunnel you will be forced to stop using the submarine.
Swim right and destroy all crates. Next to you there are two chambers with rotating platforms. First, you must swim into the right chamber. When you get inside it you must swim clockwise and stay close to its walls. This will allow you to safely reach the lower hole marked in the picture.
When you are on your way you must watch out for a fish that jumps out from a hole and a mine near to which you can find a few crates. On the left there is another submarine. When you enter it you must destroy the lower reef and then you can proceed to swim left. Just like before, you must destroy all reefs and other interactive objects.
In the last part of the stage you can encounter a Purple Gem that swims in the upper part of the area. When you get it you must reach a neighbor tunnel in which you can find a portal that allows you to leave this level.