Located in the Bay of Fundy, near Eastport, Maine, Treat Island is a unique facility that provides a natural weathering environment for concrete, masonry, and aggregate test specimens. The location has both a beach test area, with a 22-foot tidal change, providing two daily wet/dry cycles, as well as a pier facility to provide additional testing area without the wet/dry cycles. The location also provides about 150 freeze/thaw cycles per year. The site was started in 1936 in conjunction with USACE plans to develop hydropower in the bay. Multiple historically-significant concrete-related field durability research programs have been conducted here: effect of water/cement ratio, air entraining admixtures, corrosion inhibitors, effect of size/thermal mass, fiber-reinforced concrete, polymer-modified concrete, roller-compacted concrete, prestressed concrete, very-high-strength concrete (predecessor to UHPC), and many others.