I took 4 years of high school German and 4 years in college and minored in it. I spent a summer in Germany living with a family in northern Bavaria and was essentially fluent at one point. However, when I was in the Netherlands on my honeymoon a few years ago I did not understand Dutch at all. On the mainland of Holland, nearly everyone spoke English and communication was not an issue. However we also spent 5 days on an island off the coast of Holland, Texel, where very few of the inhabitants spoke English. The island is a beach resort and mainly caters to Dutch and German tourists, and I actually ended up speaking German most of the time there!