Here are some photographs of a nursery web spider (Pisaurina mira) along with approximately 75 newly hatched spiderlings. She guards the hatchlings until they are older. The adult was a thing of beauty, especially when viewed large so you can see the hairs. There was a red milkweed beetle head on a nearby leaf, and the plant itself was devoid of anything but spiders. Hunting spiders like this one probably don’t help monarch populations.
I’ve never seen them do it, but apparently the adults are completely comfortable on water, and can even submerge themselves if threatened. They’re related to fishing spiders, so that’s not a complete surprise.
Photographed at Natural Lands Trust’s Hildacy Farm Preserve in Media, Pennsylvania. I can’t find any information on whether this species is native to North America, other than finding it listed on invasive.org. The species also is distributed in western Europe.