Plum Island has two types of paddling. One is the beautiful and quiet waterways on the inland side where you can view beautiful birds along the way. Watch out for the occasional motorboat, though. Many drivers are respectful, but many have no idea how to boat safely when other watercraft are around, namely us kayakers. Alternately, there is the Ocean side, and some people do a trip with the tide to start in the inland side and make it out to sea in time, but we probably will not try this.
I have two friends who paddled out to the oceanside at different times. Both were seasoned kayakers. One lost his kayak along with his two buddies, and he swam to shore and his friends were grabbed by the Coast Guard. Someone later found his kayak washed up further down shore. My other friend and his buddies made the 6 o'clock News with a Coast Guard rescue for all three. The waters can quickly bring someone in a wetsuit to hypothermia. It is colder than you think until you are bobbing without your kayak praying for help. You have no idea when you start out what the wave height is going to be when you come around the corner to the ocean side. Unfortunately you are already committed. I will recommend staying to the sides of the inland waterways.
The waterways are an intricate maze of paths between tall grasses and sandbars. It is easy to get confused on the return trip. Places that had water when we launched at high tide were now low and impassable due to sandbars. We were now very clear on understanding high and low tide, even for these unseemingly calm waterways. For a better view of the waterways shown below, Go to Google Maps
Where to Launch
Just as you enter the park and pay your daily admission, you can park at the first parking lot on the left, adn then cross the road with your kayaks and head down the path to the boat launch. Ideally, you could just drive down there and drop off the kayaks and then go back and park, but in the summer parking is at a premium and you could come back to no parking spaces left at all. This parking area is shared with visitors to the Visitor's Center as well as the path to a very popular beach where you can swim. The Google Map below shows the parking area on the right and the ramp on the left. You can go to Google Maps to see more information.