Orbweavers
If you are trying to escape the sun in the shade of overhanging tree branches, you are inevitably going to get spiders in the boat. These are almost entirely harmless orbweavers - they are not aggressive and don't bite, and are not poisonous to humans, at least no more poisonous than a honey bee. That said, our brains are programmed at the most basic level to fear spiders, and I don't like them any more than anyone else. Just calmly knock it out of the boat.
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