After playing Dave The Diver for a bit and getting to the second chapter, you'll unlock a special type of gear called charms. These can be equipped through the chest on the boat, and provide special effects to Dave. You can only have up to two charms at a time.
At random points in the story, you'll find an Octopus twice and it'll take you to a place where you can get a random charm. Both of these charms are quite good and they can help you evade an enemy's attack and defeat it easily.
Octopus Bracelet Location Guide
To find the Octopus Bracelet, you'll first have to get to the second chapter of the main story where you'll be trying to find a pink chest for Duff. During this quest, you'll get a machine that will let you get through a metal door, which is required for getting the first charm provided by the Octopus called the Octopus Bracelet.
You can find the Octopus around the same time when you try to find items to make a Sea People Language Translator. To do so, jump into the water and go straight down on the left side of the Blue Hole. As you reach the depth of around 60 meters, your camera will pan to a strange carol on a platform (shown in the picture above).
The carol will turn into an Octopus and it'll throw ink in your face. Dave will then decide to follow the Octopus and catch it. While following it, you don't have to worry about its speed as it stops automatically if it gets too far away. It'll take you to the wall on the far left side where it gets through a small hole.
To follow the Octopus, you'll have to use the machine provided by Duff to remove the metal door. As soon as you enter, the Octopus will go into another hole where you can't follow it, but you'll find the Octopus Bracelet lying on the ground. This charm will be cleaned as soon as you exit the water and you can use it on Dave.
If you're defeated in a battle before exiting the water, you can only take one item back out since Cobra will have to rescue you.
Make sure that this item is the Bracelet as you might not be able to get it again.
Upon equipping, the Bracelet allows you to perform a small dash every few seconds. This dash might not seem as good by itself, but it can be amazing when it comes to evading a shark's attack or swimming while you're encumbered due to the extra weight. Since you unlock it during the early game, it can be the best charm you get for a while.
Octopus Weapon Charm Location Guide
To get the second charm from the Octopus, you'll have to get quite far into the story. As you escort the Sea People down to the depths, you'll be blocked by a bunch of boulders. They'll ask you to take a nail out of the ceiling but you'll have to get stronger gloves for that. It'll take Dr. Bacon a couple of days to get you these gloves.
Once you get them, you can start looking for the Octopus near the giant whale bones. This is a special room that always spawns in the Blue Hole Depths. As soon as you get to the room, your camera will pan to a pile of moving rocks. Once you get close, the Octopus will come out and throw ink at you once again.
This time around, the Octopus will squeeze through a wooden plank that's blocking the hole in the ground.
You'll have to pick up the boulders it was hiding under and drop them on the plank a couple of times to open the way.
Follow the Octopus through the passage and it'll then squeeze through a boulder wall (not the same wall that you need to break in the main quest). While doing that, it'll drop the second charm for you that can be picked up and the boulder wall will also break down. You can't follow the Octopus past this, but it does unlock an easier passage to the Sea People Village.
As for the Octopus Weapon Charm that you get from this interaction, it directly provides your weapon a 15 percent damage boost. This doesn't apply to your Harpoon, so you'll have to upgrade your weapons a bit if you want to make use of it. This is the perfect charm to use if you know you're about to fight some bosses.
Although, there are a bunch of bosses in the game that won't even allow you to use your weapon, especially during the late game.
Eventually, you'll unlock an extra shop in the Sea People Village that will also open up some more weapon upgrades. The high damage of these upgraded weapons combined with the charm can easily let you defeat even the most formidable enemy.