My al,ost 5 y/o twins did a stingray event while at another location. It was very low key and the LOVED it!! Still are talking about it today, 1 month later. With ours tho, my kids got inthe water with the sting rays, petted them., fed them etc along with being able to touch eels, sea cucmbers, starfish, sponges etc. We haven't done a dolphin one with them yet, but if they can get IN the water with them, they will have fun. OUr stingray acted like a puppy and came up to their ankles and flapped at them wanting to be petted!!
While going thru pix, my kids also tell me all the names of the fish.
Good luck choosing.