Tregaarden's Christmas House is Drøbak at its most oddball: a year-round Christmas shop in a town that receives Norwegian Santa mail. It can feel kitsch, but it is local kitsch with a long enough story behind it to be worth a look.
Drop in if you are already walking through the centre, especially outside the actual Christmas season when the joke lands better. The shop is not an essential sight like Oscarsborg, but it gives Drøbak a personality most Oslofjord towns do not have.