A second iteration of the Water Horse prototype was tested at the Tanana River Test Site in Nenana, AK in the summer of 2021. The Water Horse is an oscillating energy system that harnesses the gallop phenomenon where a bluff body immersed in a flow induces alternating lift through vortex shedding and fluid-body interactions. This updated system incorporated changes to bluff body size, oscillating frequency, and PTO design based on lessons learned from testing completed in 2020. The new prototype incorporates upstream and downstream systems to investigate coupling effects between adjacent oscillators. This presentation will review design changes and summarize the results of data analysis on correlations between flow velocity, spring stiffness, generator load and the efficiency, frequency, and amplitude of the system. Anecdotal lessons learned will also be shared. This work was funded by the DOE Water Power Technology Office.