This map takes place at a dam. The Bloons travel along the pathway located at the top of the dam. They enter from both the top and bottom simultaneously and exit to their respective opposite sides.
The dam blocks line-of-sight from towers placed on the ground; however, towers can be placed on top of the rocks, which will allow them to see over the dam.
There are two panels located on the dry side of the dam. Clicking on a panel five times in succession will reveal a button. Clicking on both of the panels' buttons will reveal a third button in the middle. By paying $5000 to remove the object, the dam will open and flood the rest of the map, replacing all but the highest land with water. Any non-amphibious towers placed on lower elevations will be sold automatically, apart from the Sun Temple and True Sun God.
As of Version 18.1 and later, the buttons must be used in the proper order.
- Open upper panel without pressing the button
- Open lower panel without pressing the button
- Before the panel closes press the upper button, the button should turn from red to green
- Before the panel closes press the lower button, the button should turn from red to green
- The center button should open.
- With Village and Alchemist, Permaspike can still reach out to the middle of the map.
- Towers are unable to be placed on the sloped dam.
- The elevated rocks at the back are good spots for Sniper Monkeys.
- This map is very hard to do Primary Monkeys Only without powers and is only possible with Admiral Brickell, Adora, Pat Fusty, Etienne or Obyn Greenfoot because very few Primary Monkeys can reach the Bloons.
- For Magic Monkeys Only, starting off with a Hero is a must, as it is incredibly difficult to complete with just a 1-x-x Wizard (Alchemist can see over as well) as the only viable starting tower, considering the poor Line of Sight visibility by the massive dam blocking the only placeable land spots.
- Carrier Flagship and Arctic Wind are an incredibly useful combination here, as they allow for land towers to be used.
- Main article: Flooded Valley/Strategies
- This is the sixth Expert Map to be added in BTD6.
- When flooded, this is the map with the most amount of water of any map in the Bloons TD series.
- At least 100 Subs can be placed on this map alone when the map is fully flooded.
- Towers in radius of an Arctic Wind Ice Monkey will still be sold when flooding the map.
- Pat Fusty, who can be placed on land and water, has weird interactions when flooding the map.
- When he is placed in the dammed portion of the map, he will be floating with the water at waist level.
- If he is placed in the valley portion before flooding, he will stay standing on the valley floor, so that only his hair peeks out from underwater.
- If he is placed in the flooded region after flooding, he will be standing on top of the water.
- If the player places a Portable Lake on the ground and place water towers on it, these towers will be affected by Line of Sight by the dam's slope. When flooded, the Portable Lake will also be sold, but these towers will remain on the map and become underwater after the flooding, and the sight blocked by the dam will be removed.