We had the boys joint birthday party on September 26th. Bryson's birthday was on the 24th and Carter's birthday was May, 5th. We didn't have Carter's birthday back in May because his arm was still broken. Thankfully Bryson said it was alright and they both have a lot of the same friends so it all worked out.
We had their birthday at the Japanese Water Park. It was a blast as usual. It was the first time for every family that we invited to the Water Park so that made it special for everyone. We were so happy to share a place that we enjoy going to. They all said they would visit there again next summer when it opens back up.
We pretty much just let the kids lose and they just roamed the whole park. It's not like an American park so don't worry we aren't dead beat parents. ;) There are two large slides, one tube slide, the lazy river and then a shallow area with a few cement slides. Though it may not be much it's enough to let them roam and feel safe doing it and the price is awesome. For our family of 5 it costs less than 20 dollars so it's some cheap fun.