There are several trails in the park. I do not know the length of any of them. There are maps on the website for the park that might provide an answer.
There are a few trails. They start at the Biden Center. They are about 2-3 miles along.
There are a few hiking trails. There's the main loop with both paved and fine gravel and there are other ones. One trail starts/begins at the Biden Center and another one starts off the main trail near the campground. That one is, I believe, the dunes trail. Further down from the dunes trail near the main loop is also a marsh trail but it's interesting because at the beginning of the trail, there's one side of land that allows hunting and the other side that does not.
The hiking trails are mostly not near the beach. They can be accessed from two different entrances - City of Lewes and City of Rehoboth. Their distances are about less than 2-3 miles on pavement and sand/rock mixture.
https://destateparks.com/Trails
There were many people riding bikes, but my family was there only for the beach so I can confidently advise.
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