My parents used to take us to swimming holes as babies all the time, if you’re knowledgeable about reading water and being able to spot what’s dangerous then you’ll be able to find tons of swimming holes that are baby appropriate. If you don’t know anything about rivers then lake Champlain has tons of baby safe Sandy beaches, there’s also Waterbury reservoir and a few other smaller lakes. Keep an eye on news about different beaches in case of closures for algae blooms (which are unfortunately becoming more common) it’s usually posted by whatever municipality manages the beach.