Maryland Natural Resources Police said Monday that McKean's body was found in 25 feet of water about 2.5 miles south of her mother's residence, where the canoe had launched. Authorities used aviation and underwater imaging sonar technology to find her body.
The authorities said they would resume their search for Gideon on Tuesday.
David McKean wrote a long Facebook post Friday in tribute to his wife and young son, calling his wife "the brightest light" he had ever known.
"She was magical — with endless energy that she would put toward inventing games for our children, taking on another project at work or in our community, and spending time with our friends," he wrote.
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He described Gideon as a child who had deep passions and spent hours reading, learning about sports and "trying to decipher the mysteries of the stock market."
"But he was also incredibly social, athletic, and courageous," McKean wrote. "And he was brave, leading his friends in games, standing up to people who he thought were wrong (including his parents), and relishing opportunities to go on adventures with friends, even those he'd just met."