have a look on e-bay some 2 for 1 available

If you look on Ebay the best discount tickets/flyers to get are the ones where for Aqualandia it's 11 euros adults and 7 euros for a child for a day visit and 8 euros adult and 5 euros child after 4.00pm. Mundomar is 8 euros adult and 5 euros child and then 5 euros adult and 3 euros child after 4.00pm and one child actually goes completely free after that time. Loads of seller usually have then on a buy it now price for a couple of pounds and they're well worth buying.

There are no dates on them so you can use them anytime and I have never seen any offers that will beat them or come anywhere near the discount price. Each ticket is also for use for up to four persons so you don't even need to buy one each.