The lovely 6 spotted fishing spider (Dolomedes triton). This species is the most aquatic of all the North American fishing spider species. It will often hunt mosquito larvae, tadpoles and small fish. It will dip its two front legs into the water waiting for vibrational queues of potential prey. Once detected, it will either skirt across the surface or dive underneath to inject a lethal bite to its victim’s head.
They are harmless to mammals. And coincidentally this exact individual is one of only two spiders (out of thousands I have handled) to have bitten me. I grabbed him when he got loose in the lab. My finger was a bit itchy. They aren’t likely to bite otherwise.