If you’re paddling the river, be sure to ride with the tide. The direction of the water changes 4 times throughout the day. Make life easier on yourself (and keep safe) by paddling with the tide. If you’re motor boating or sailing, knowing the tide is important for navigating shallow areas.

http://tidesandcurrents.noaa.gov/
http://www.saltwatertides.com/dynamic.dir/delawareriversites.html