A mat having a core that provides strength and rigidity to the mat, and including a structure of a sheet, elongated members, a frame, compartments, or combinations thereof and at least one outer layer associated with the core and made of a sheet, elongated members or combinations thereof. The core and outer layer(s) are integral or are joined together, and the structure of the core is made of one or more environmentally resistant materials to provide an extended service life when encountering rain, snow or other weather conditions that would eventually degrade wood. The mat has a load bearing capacity that is able to withstand a load of at least 500 to 800 psi or even 1000 psi without permanently deforming the core. Bumpers are preferably provided upon sides of the mat to protect them from damage due to transport or installation of the mat.