Environmental theatre, similar to site-specific theatre, aims to eliminate the barrier between actor and spectator by performing works in non-traditional spaces such as shipping containers, quarries or elevators. The form was made famous by Richard Schechner in the 1960s and 70s, who in turn was influenced by concepts introduced by Jerzy Grotowski, a Polish theatre practitioner who experimented with seating the audience within the performance space. In environmental theatre, the found space or location influences the performance. – Justin Cash
Encyclopaedia Britannica Article explaining the major exponents of the environmental theatre form.
The New York Times Historical 1974 article about environmental theatre in the early days of the movement in New York City.
Kruesi, Larrisa Academic detailing environmental theatre.
TDF Theatre Dictionary Useful entry on the characteristics of environmental theatre.