We will be in both Belgium and Netherlands on that day. What can we expect regarding closures, crowds, etc.?
In the Netherlands May 1st isn’t a public holiday. It is a Sunday this year, but that won’t impact things either. Everything you could possibly want to see and do as a tourist will be open. You should however expect crowds, due to the school holidays and the tulips. When exactly will you be in the Netherlands? There are some other holidays at the end of April and early May that can have an impact. Although this impact will only be in terms of crowds, not closures.