The Tidal Coast
The Tidal Coast is a location found in Wario Land 3 of the Wario Land series. It serves as the fifth of six levels found on the north side of the Music Box World. Wario can come here after he has found the second Music Box in A Town in Chaos. The Tidal Coast becomes accessible simultaneously with another level: The Bank of the Wild River.
The Tidal Coast takes place in a craggy area directly at the coast. Most of the level is flooded, and the only dry spaces are atop of rock formations. The most common enemies in this area are Spear-bots and Hammer-bots. Several caves can be accessed from the flooded area, including an underwater cave inhabited by Octohōn, another submerged cave filled with air bubbles, and a cave full of vines and thorns. The most notable feature of this level is the presence of tides. There is low tide at daytime, while there is high tide at night, which will submerge some of the rock platforms. The tides also affect a block floating on the surface.
Treasuries
Grey Key: The Yellow Spell Book
The Yellow Spell Book is hidden inside the Grey Treasure Chest, which itself is located behind a wall of Bonfire Blocks at the end of the level. The respective key needed to unlock the chest is located right above it. The player has to make good use of the Hot Wario and Bouncy Wario reaction abilities to complete this part of the level.
Once Wario found the Yellow Spell Book and the Trident from the Bank of the Wild River, he can use both items to summon a heavy lightning storm above the south side of the Music Box World. Numerous bolts then rain from the sky onto the land. One of the bolts hits the river on that side, tearing the ground apart and revealing The Steep Canyon.
Red Chest: The Stone Foot
The Red Treasure Chest becomes reachable after Wario has picked up the Red Gloves from The Steep Canyon, which allow him to pick up and throw enemies. With this technique, Wario can uncover the Warp Pipe leading to the cave filled with air bubbles, where the treasure is located. While the air bubbles mostly serve as obstacles, Wario has to use one to reach the Red Key. Deeper inside the cave he then finds the treasure chest he is looking for.
The Stone Foot is an artifact that has the power to create massive earthquakes. By throwing it to the ground, Wario causes the entire Music Box World to shake, which fissures both The Volcano's Base and The Steep Canyon. The earthquake also drains the water in The Stagnant Swamp. In all three levels, new paths become available for the treasure hunter.
Green Chest: The Propeller
Wario aquires the means to retrieve the Propeller from the Green Treasure Chest as soon as he rescued the Wire Wizard from the Bank of the Wild River. The treasure itself is located in the cave filled with vines, which can only be accessed during the night. The high tide then makes the entrance to the cave reachable. Before he can hope to obtain the treasure, though, Wario must first find the Green Key in another cave. The Garlic from the Tower of Revival is needed here. After finding both, Wario gets the Propeller.
The Propeller can be used to repair the strange devices in A Town in Chaos. When connected to the machines, the Propeller will produce air currents which will carry Wario upwards.
Blue Chest: The Green Bracelet
In order to get the Green Bracelet from the Blue Treasure Chest, Wario first needs to find the Sapling of Growth from A Town in Chaos. The object will make the Octohōn in the level grow to a menacing size. The improvement of size and strength then allows them to smash through the barriers that hold them captive. That way, Wario becomes able to explore the Octohōn cave, where he can find the Blue Key and the Blue Treasure Chest. The player should watch out for the Octohōn though, since their growth makes them more dangerous now.
The Green Bracelet is an accessory encrusted with three smaller objects. Collecting it does not affect the Music Box World in any way.
Reaction Abilities in this Level
Screenshots
The coast at low tide. 
The coast at high tide.. 
The vine cave. 
The Octohōn cave.
