Playgrounds / parks for infants/children in Negombo and Colombo

Hello fellows expats!
I will be in SL for 3 months starting May and I will be living in Negombo for 1-2 weeks and then in the capital. I am traveling with my son (6months old )and I am interested where I can take him for a stroll or meet other children and play. We like to spent a lot of time outdoors.
Where do you take your children? Do you organize play-dates for the kids?
Thank you all for your responses.
Lavi

You can go to the Negombo beach park
Yes you can invite all the expat to meet in a specific day in a specific place
If you could visit during Sri Lanka's New year day (14th April), durin the month of April, there will be a lot of  new year festivals everywhere.

Thank you Mal. I will be there starting May so I will miss all those festivities taking place in April.