You must visit Den Haag which is right along the coast of the North Sea. BEAUTIFUL!!!
Important information: You will need to take a train to this location from Amsterdam Centraal Station. There are two train stations in Den Haag and you need to get off at the Den Haag Centraal Station. (the other location would be Den Haag HS). The Den Haag Centraal is more convenient, and only five minutes from the center of the city. Round trip will cost about 25 euro.
YOU NEED to take the TRAM (Tram 9) the North of Den Haag (10 min. bus ride) and visit the beach called Scheveningen. You pronounce s-khay-ve-ning-uh. Very difficult. Cost for a bus ride is only 2.60 euro round trip!
Here are a few pictures. This small town is wedged against the seashore. This is the Netherlands BIGGEST costal resort. This location attracts more than 9 million people every year.