There have been so many people looking for links to splash pad parks, lakes and more! I am including a bunch here! Check them out!!
http://njmom.com/things-to-do/splash-water-parks-in-nj/
http://www.jerseyfamilyfun.com/new-jersey-splash-pads/
http://newjersey.mommypoppins.com/njkids/best-water-playgrounds-in-nj
Make sure too to check out some of the swimming lakes in the area! Harry Wright! Atsion!
http://njmonthly.com/articles/jersey-living/great-lakes-where-to-make-a-splash-in-nj/
http://newjersey.mommypoppins.com/kids/lake-swimming-in-new-jersey
http://www.swimmingholes.org/nj.html
Of course, always check first before you venture out to make sure all venues are still open! Happy splashing and swimming!!!!