The performance of a free-space optical (FSO) communications link in a maritime environment was evaluated during two field trials conducted off the mid-Atlantic coast near Wallops Island, VA, in July and September 2009. Bidirectional, ship-to-shore data links operating at 2.5 Gbps and utilizing commercial, single-mode adaptive optics terminals were set up between a lookout tower located on Cedar Island, VA and a Johns Hopkins University Applied Physics Laboratory research vessel over a range of 2-22 km (optical horizon). This paper presents the test configuration, discusses the overall performance of the FSO channel, and compares it to the available turbulence and weather measurements. Additionally, modeling of the link configuration is presented, and comparisons are made to data measured throughout the experiment such as received power, received beam diameter, and local The performance of a free-space optical (FSO) communications link in a maritime environment was evaluated during two field trials conducted off the mid-Atlantic coast near Wallops Island, VA, in July and September 2009. Bidirectional, ship-to-shore data links operating at 2.5 Gbps and utilizing commercial, single-mode adaptive optics terminals were set up between a lookout tower located on Cedar Island, VA and a Johns Hopkins University Applied Physics Laboratory research vessel over a range of 2-22 km (optical horizon). This paper presents the test configuration, discusses the overall performance of the FSO channel, and compares it to the available turbulence and weather measurements. Additionally, modeling of the link configuration is presented, and comparisons are made to data measured throughout the experiment such as received power, received beam diameter, and local Cn2.