You can get the majority of the Blue Coins during Episode 8, but there are a few that are a bit more restrictive. For example, there are a few Blue Coins that can only be gotten during Episode 4, as that is the Shine that takes place is a new area. As before, let’s take care of the episode-specific coins first, then move on to the general ones.
Blue Coin #1
You can get this coin during either Episode 1, Episode 2, or Episode 4. On the main beach, there are a bunch of Cataquack enemies that will toss you into the air if you get too close. The majority of them are blue, but there is a single red one standing out from the crowd. Spray this Red Cataquack to stun it, then jump on it to make it spit out the Blue Coin.
Blue Coin #2, #3, #4, and #5
The next four Blue Coins are all found in Episode 4, inside the area with the Sand Bird. As the Sand Bird moves around, you will pass by some clouds that have the Blue Coins on them. Two will be before the bird turns to its side, the third right when the bird turns, and the fourth one will be near the top of the central tower.
Blue Coin #6
You will need to be in Episode 6 in order to get this coin. Yoshi is required for this and the egg can be found on the little peninsula, while the fruit can be found at the cabana near the starting point. Once you have Yoshi, there is some orange goop right next to the cabana at the starting point. Dissolve it, then spray the Dune Bud until the Blue Coin is revealed.
Blue Coin #7
With Yoshi still in your possession, head to the Shine Tower area and locate the beehive underneath the wooden structure there. Spray it with Yoshi to knock it down, then eat all of the bees to get the Blue Coin.
Blue Coin #8
At the beginning of the level, turn around and locate the island with the palm trees on it. Head on over there and climb the largest tree, where you will find the Blue Coin at the top of it.
Blue Coin #9
While in the same area as #8, jump down to the swing and spray in the opposite direction as the coins to push the swing that way. It will probably take two full sprays to get enough momentum to grab the Blue Coin.
Blue Coin #10, #11, #12, and #13
There are four Blue Coins in the water and they can be found in every episode, except for Episode 5. They will all be found between the island with the trees and the reef. Two are stationary in the water, but you should be able to see the coin spinning, as the waters are pretty clear. The other two coins will be following schools of fish, so expect the coins to start moving with the fish when you get near.
Blue Coin #14
At the beginning of the level, there is a little shack that has some fruit for Yoshi inside of it. On the inside ceiling of this shack will be a Blue Coin.
Blue Coin #15
There is a ledge behind the fruit shack/cabana, where you will find the Rocket Nozzle box that unlocks it for this level. You can get to it by hovering from the nearby slightly higher ledge, if you haven’t unlocked it already. Once you get on the ledge, clean the graffiti there for the coin.