Hydro is a Territorial Control map, and one of the six initial maps included with the game's release. So far, Hydro is the only official Territorial Control map, possibly due to the complexity and difficulty of designing such a map type.
The goal of Hydro is to take over the entire map by capturing "territories". Each game is randomly selected from the six available layouts in a "point against point" game in which both teams must capture the opposite control point while protecting their own. After a team successfully captures the enemy control point, the next round will start, taking place in a different area of the map (which is also randomly generated). After a team captures all four territories, the attacking team must capture the enemy team's base while the opposing team defends for their life. If the Base point is captured, the attacking team wins the round. When the next round begins, territories are reset and a new random game is selected.
In any round of Territorial Control (except in RED/BLU Base rounds), if a control point is not captured within the eight minute time clock, the game will go into Sudden Death mode.
A large radar dish. The capture point is located in the center.
Entrances from the flood area: The radar dish is connected to the flooded area of the map via a pair of ground level tunnels.
Entrances from the turbine room: The turbine room is connected to the radar dish by a large suspended rock formation. This formation is split into two paths with a hole in the middle, the paths splitting left and right at the radar dish end, and connecting to the turbine room at the other end.
Entrances from the bridge area: There are three paths from the radar dish to the bridge area. The first is the large path on the right hand side of the map. The other two paths are to the left of the main path, one of which goes off to the left (either down to the ground or onto a catwalk), while the middle one connects directly to the raised rocky ledge of the bridge area.
Under the stairs: All of the stairs in the radar dish area can be shot through, and are a common place for Sentry Guns.
BLU CP1: The Power Plant
The Power Plant capture point.
The turbine room capture point is located on a metal bridge suspended in the middle of the building.
Entrances from the flood area: The flood area connects to the turbine room via three paths. The two left paths connect to an open area outside of the turbine room, which in turn allows access to either the lower area of the building, or the room with the large pipes. The third path is on the right, and goes from the flooded area through a small tunnel and meets with the lower left path.
Entrances from the bridge area: The turbine room is connected to the bridge area by a main road, sewer tunnels, and the ventilation system. The main road leads to an area outside of the turbine room that allows access either to the lower or middle levels of the building. The sewers connect the bridge area to the lower area of the turbine building, while the vents connect the roof of the bridge area to the room full of pipes next to the main building.
Entrances from the radar dish: The radar dish connects to the turbine room via a rock formation. Once inside the building, the exits lead either onto the cat walk, or follow the stairs down to the middle of the room.
Service room: There is a small windowed room that is next to the bridge. This room is often used as a hiding place for Engineers as it allows them to see attackers without being shot at.
RED CP2: The Dam
The Dam capture point.
The flood area control point is located on top of a raised concrete block in the middle of a large open area with standing water.
Entrances from the bridge area: The bridge area connects to the flood area via an upper and lower path. Both paths converge in a cavern that then splits into an upper, lower, and sewer path. The upper path connects to the ledge overlooking the bridge. The lower path follows the water along the ground under the ledge. The sewer path exits in front of a truck just next to the bridge.
Entrances from the radar dish: The flood area is connected to the radar dish by a pair of small tunnels. One tunnel comes out near the flood area spawn room, while the other comes out behind the flood area point.
Entrances from the turbine room: The turbine room connects to the flood area via three paths. One path leads from the ground level and to the right, and eventually connects to the long stairs in the flood area. The second path follows the ground around to the left, and can either stay at ground level, or connect to the top of the long stairs. The final path branches off the second path, and leads down a small tunnel to the water area behind the flood area capture point.
Second story windows: The flood area spawn room has a second floor that Snipers often use as a nest.
BLU CP2: The Warehouse
The Warehouse capture point
The bridge area control point is on a low concrete bridge outside of a large building.
Entrances from the radar dish: The bridge area is connected to the radar dish via three paths. The main path hugs the left side of the map. The second path connects the bridge area ledge to the middle of the radar dish area, while the right path comes out on the ledge on the radar dish side.
Entrances from the flood area: The flood area connects to the bridge area by two paths. The upper path connects exits above the flood area capture point, while the lower path comes out in the water behind the flood area capture point.
Entrances from the turbine room: The bridge area connects to the turbine room via the road, the sewers, and the vents. The road leads to a small area that connects to the middle and lower levels of the turbine room. The sewers lead to the lower level of the turbine room, and the vents connect to the room full of pipes adjacent to the main building.