This dataset publication provides access to seven years of high-frequency sensor data from three lakes: Giles, Lacawac, and Waynewood. These lakes are located in the Pocono Mountains region of Pennsylvania, USA and have been the site of long-term monitoring and research. Lake Giles is a relatively clear-water low dissolved organic matter oligotrophic lake in a largely protected watershed. Lake Lacawac has higher dissolved organic matter concentrations and is considered a dystrophic brown-water system; it is also in a highly-protected watershed. Lake Waynewood is a relatively productive eutrophic lake with a larger watershed that is mixed agricultural, forested, and residential use. High-frequency sensors were deployed on sensor lines at the deepest point in each lake. Measurements included temperature and dissolved oxygen through the water column, fluorescent dissolved organic matter at the surface and bottom, and chlorophyll fluorescence at the surface of each lake. These data are collected at a frequency of 10 to 30 minutes and are available in the data packages GilesHighFrequencyData.csv, LacawacHighFrequencyData.csv, and WaynewoodHighFrequencyData.csv. Data from weather stations located adjacent to each lake can be found in the data package PoconosWeatherStationData.csv. Additional long-term limnological data (four decades) for Lakes Giles, Lacawac, and Waynewood are available in the data package edi.186.8.