It is believed that Steepelchase originated in Ireland sometime in the 18th century.
Steeplechase is a timed event. Most of the obstacles (which may or may not involve water) are metalic structures with "soft" (foam, plastic, etc.) bushes. The horses race in groups, jumping the obstacles. Some of the fences may be post and rail, often made of wood.
See the National Steeplechase Association HERE.