What is a crayfish party like in Sweden/Scandinavia?

In Stockholm, they often take place on boats through the archipelago (at least the one I attended for work did). It's beautiful in summertime, and the sun sets so late ("midnight sun") so the parties often last late into the night.

Food tends to be similar to typical smörgåsbord: hard bread, cheeses, boiled potatoes with dill, sill (pickled herring) in various sauces, meatballs. Brännvin (aquavit, distilled spirits) or beer to drink, or sockerdricka (non alcoholic) which is sweet carbonated water.. but nearly everyone will be drinking alcohol, and a lot of it.

As I mentioned, the one I went to was work-related (many are), so the schedule included some games, promotional talks about the company, etc. Dinner was buffet style and nicely presented, with a "dansband" playing music. Swedes tend to be reserved otherwise, but become very talkative whilst drunk so it's an interesting chance to get to know your coworkers.

Copy kräftskiva into Google and search images if you want to see pictures.