Is Dolphinarium the Marineland? If so here is their website:- http://www.marineland.es/marineland/mallorca/index.php?wlang=en

Also I've heard the Pirates of adventure show is good:- http://www.piratesadventure.com/

Marineland great for 5 year olds, if you are hiring a car there are usually discount vouchers on their website. if you are planning to go on an excursion then NO FRILLS are cheaper from the north of the island than tour operaters and i and many others on here would recommend them to others, we have used them a few times without problem.
pirates is a great show for all the family,The houseofkatmandu while educational and informative, may be a little scary at 5, my 5 & 7 year olds were not keen last year
The aquaparks are a good day out, we prefer El Arenal as there are less groups of lads knocking about, but shows are better at Western Water Park. Alcudia Hidropark is a bit small, but at age 5 should be enough to entertain.
Have a great time wherever you go

Thanks to you both and sorry meant marineland, i shall look at going to both whilst out there.

Pete