Oldest Dolphin/Whale pools/tanks

The photo is from the 1960s. It was taken at the first Sea World which was San Diego. You can see Mission Bay in the back ground.

 

Oh ok,

This was why I thought it might have been Ohio:
(Wikipedia)

"Milton C. Shedd, Ken Norris, David Demott, and George Millay brought SeaWorld to life, yet that was not the initial idea. The four graduates of UCLA originally set out to build an underwater restaurant and marine life show.[8] When the underwater restaurant concept was deemed unfeasible, they scrapped those plans and decided to build a park instead, and SeaWorld San Diego was opened on March 21, 1964.[9] With only a few dolphins, sea lions, 6 attractions and 22 acres, the park proved to be a success and more than 400,000 guests visited there in just the first 12 months.

After considering other locations in the midwest, including the Lake Milton/Newton Falls area west of Youngstown, Ohio, it was decided that Aurora, Ohio would be the new home of a SeaWorld. The Aurora site was approximately 15 miles northwest of the Lake Milton site, and 30 miles southeast of Cleveland.[10] By this time the founders of the company had captured a few more species of animals including an Orca that would call the new facility home. The Ohio site would prove to be difficult to maintain."

 

I've never been there but I know that the dolphin pool in Festa Dolphinarium in Varna is quite small too:
http://upload.wikimedia.org/wikipedia/commons/a/a9/Dolphinarium_Varna.jpg
The pool is 6 metres in diameter and 3 metres in depth and holds 1200 cubic metres of seawater.
The dolphiarium currently holds 8(?) dolphins and has a small backstage tank too, with underwater viewing.
The dolphinarium was opened in 1984 so it's not very old compared to some others.

 

Most dolphin tanks in indonesia is tiny, especially the Taman Safari one, the largest is probably the one in Ocean Dream Samudera