Ecomare

When the water at high tide has reached its highest point, it will remain like that for a very short period of time. Everything which has been captured by the waves rolling back and forth will have time to wash ashore. If there is a lot of material, then an obvious strip of random objects (flotsam), seaweed and shells will form along the entire length of the beach, the so-called high tide water-line or the flood mark. Sometimes, there are several flood marks. Because the wind does not always push the waves far up the beach each time, the flotsam does not always lie along the same line.

There are all kinds of interesting objects to find on the beach. For instance, it is not uncommon to find 'egg clouds' from a whelk, an object the size of a tennis ball and containing eggs resembling small yellow bladders. Eggs from the lesser spotted dogfish and the thornback ray (mermaid's purse) can also be found on the beach. In the summer, jellyfish strand on the beach and die. Carapaces from cuttlefish can be found in the autumn. And of course, one can always find shells on the beach the whole year round: cockles, mussels and razor shells intermingled with deserted 'houses' from whelks, flat sand gapers, piddocks and spisula. Because there is always something edible lying between all of these materials, there are often gulls and sanderlings, in particular, rummaging together a meal. Unfortunately, not only natural materials lie on the beach.
All sorts of objects wash ashore. Visitors also leave rubbish behind and lost objects. The flotsam is made up of remnants from plants and animals and things dumped from ships or a lost cargo. Most people unintentionally find something on the beach, but there are others that consciously search the beaches for finds: the beachcombers. There are lots of useful items to be found on the beach after a storm, but the most unthinkable objects are ship loads of timber, entire crates of whisky or cigarettes. 'Unfortunately', the modern container transportation has not made life better for the beachcombers! Less desirable and even dangerous are the medicine, paint cans and other toxic materials that wash ashore after being dumped at sea.

Despite ever increasing number of strict laws, lots of rubbish is still dumped in sea. Sometimes, it is unintentionally lost by the fisheries or shipping: objects fall overboard and nets break off. But lots of things are intentionally dumped. It is an old tradition to dump your garbage overboard when at sea. The sea is considered one big sewer instead of a nature area.
During the annual Coastwatch project, co-ordinated by the North Sea Foundation, school children and other groups gather marine litter, sort it out and weigh it. Seventy-eight kilometers of beach were investigated in 2006, in which an average of 136 pieces of marine litter were found per 500 meters. The figures vary per year, but it is still obvious that there has been no improvement. Half of the rubbish collected is slow degradable plastic. Add the ropes and nets, which are usually synthetic, then is 67% of the total made up of plastics. Around 42% of all rubbish can be identified as originating from ships. It is certainly not true that all washed up rubbish only originates directly from the sea. During spring tide or storm, lots of junk returns to the sea just to wash ashore elsewhere.
On the beach, there is not just litter that was thrown away a short while ago. There can also be litter which has been lying around for dozens of years, such as explosives from the Second World War. Large amounts of mines and explosives were rendered harmless after the war, but some of it was forgotten. For example, in the summer of 2000, 50 year-old ammunition was found on the beach of Zandvoort. The oldest human 'litter' that sometimes washes ashore consists of flint tools dating back to prehistorical times!