The number of vents varies by map. The Skeld has a total of 14 vents. There are two sets of 3-vent closed loops, and four sets of 2-vent closed loops. Mira HQ has 11 vents. These connect in one large loop, but you have to move through them one at a time. Two locations connect in three different directions, but the rest only have two connections. Polus has 12 vents. There are two sets of 3-vent closed loops, one 2-vent closed loop, and then 4 vents that are connected but you have to move through them one at a time, and the first and last don't connect back to each other. The Airship is the largest map in Among Us, but it only has 12 vents. There are three sets of 3-vent closed loops, and then the last three vents are connected, but you can't move directly from the first vent to the last vent without passing through the middle vent.