Get out your orange ladies and gentleman and head out to the streets hoping to find the best deals on other people stuff.
Amsterdamers love to party and this is one great big party for the whole of the city, and I do believe, probably the country. I say this because it felt that the whole of the country was there. This is not a day for those who cannot handle a crowd. Orange is the color of the royals so you will also see people covered from head to toe in it. You may feel a bit awkward if you forgot your orange crown, but don't fret, there is surely a helpfull soul just waiting to sell you one.
This is the one day that everyone is allowed to haul all their old junk out onto the street and hope to sell it. Locals mark out their spots days in advance and set up as early as 6am! In my experience I saw everything from tea sets to sunglasses to (yes, this is true) a stand with four kitchen sinks!
One last necessity of the day is to enjoy Heineken . . . all day long!
So with boats cramming the canals, people cramming the streets and music playing all day long, head out and enjoy this party of all parties in Amsterdam.