The only equipment needed is some large blocks of ice and thick, preferably padded, clothing. Hessian sacks or old towels have been recommended to sit on. Enthusiasts have been known to make "customized" ice blocks by freezing ropes into them to act as handles, and mixing colouring agents into the water prior to freezing.
Hazards include falls, bruises, bug bites and getting covered in mud. The bottom of the slope being used should be a wide area free from obstructions. Short grass is reported to give the best experience, due to lower drag and hence higher speed. It also hurts your buttocks less when you fall.
Generally it is an informal activity not done on a competitive basis but at least one university has held an ice-blocking contest. 
This activity can damage the grass and is often banned or restricted by park authorities and groundskeepers. For example, the city of Mesa, Arizona has four sites where ice blocking is permitted in rotation, depending on the judgement of the management. In Fresno, California the sport has been embraced by high school students, who frequent parks during late night hours in an effort to evade law enforcement officers. Ice blocking has also been featured on television on the MTV series Jackass.
When the ice you freeze is in the shape of a cylinder, the sport it similarly referred to as "Ice Cylindering".