Hazards are as the name suggests, are things in the Pikmin games that are hazardous. There are multiple hazards in both Pikmin games, including Fire, Water and explosions.
The Hazard fire is one of the four main hazards, and exists in both Pikmin games. Fire usually emits from Fire Spouts, which can be destroyed by any type of Pikmin, but also comes from enemies like the Fiery Blowhog. When a Pikmin is set on fire, it is possible to save them by blowing your whistle at them.Pikmin 2. Upon touching electricity, any Pikmin except Yellow Pikmin will instantly die. Electricity comes from Anode Beetles and Anode Dweevils, as well as the Electric Nodes. There are also electric gates which must be knocked down with Yellow Pikmin.
The third main hazard is water. Water comes in many shapes and forms, and exists in both Pikmin games. It is possible to drain water from some lakes in Pikmin 2 by breaking a rock formation. If a non-blue Pikmin gets hit by water from an enemy small bubbles will appear around the Pikmin, calling back could save them. The only enemy in Pikmin 1 that does this is the Goolix. Blue Pikmin are immune to this, and walking into lakes. If a Pikmin goes into a body of water, they will start drowning. To save them, on land call your whistle at them repetitively. Blue Pikmin (if not with a leader) can save other drowning Pikmin by throwing them, but this may make it worse.
Poison is the fourth main hazard which is quite lethal to Pikmin making them flop about all over the place upon contact. Poison usually comes from the spouts in the ground, but can also be emitted from enemies such as the Munge Dweevil.