Much has been made here and elsewhere about the ocean water temperatures off of the Jersey coastline this summer and how they had been. Upwelling (the process of colder water below the surface working up to the surface as warmer water flows away) has been to blame for dropping the ocean temperatures at Atlantic City and along other South Jersey coastal waters into the 50's and 60's. While some recovery in the ocean waters at the Shore has taken place and temperatures are easing back towards 70. There's still some cool waters near the coast and with the pattern featuring west and southwest breezes, we'll have a bit of hard time getting that warmth to the coast too soon.
While Shore water temperatures are several degrees below average for this time of the year, they're still relatively tolerable in comparison to what Lake Superior is dealing with. The middle of Lake Superior's water temperature features pockets of upper 30 degree water mixed in with other pockets of "warmth" where the water temperatures are in the 40's and 50's.
Last year at this time, a fair bit was written of Lake Superior's record warm water temperatures, with temperatures this year a good bit cooler in many parts of the big lake compared to the peak of summer last year. The late, slow start to Spring in Minnesota and Wisconsin has a lot to do with lake water temperatures on Superior being as cold as they are this year.
Anyways, the ocean's chill locally is not as bad as elsewhere...and if you want a place to cool off, head to the largest of the Great Lakes and take a dip in waters that are as cold as 39 degrees (as they are in the middle of the lake).