With such a good weather, the police has seen people swimming in the Spaarne. This is dangerous and forbidden. The following days will still be nice and warm and the Haarlem police announced that they will constantly patrol the Spaarne with the police boats. There is a fine of €140 for swimming and jumping from bridges into the river.
The police listed a number of dangers of swimming in the river where ships also sail. There can be strong currents, boaters often cannot see swimmers and the temperature difference can cause swimmers to cramp or even become hypothermic. Swimmers can also be pulled under a ship by suction.
Jumping from bridges is also dangerous and forbidden. For example, you can land on a ship that you have not seen, you can have bone fractures or a collapsed lung and you can land on sharp objects that are under water.
So better to not swim or jump into the river, not only because of the fine you might have to pay, but also because of the dangers.
There are many other safer ways to enjoy the warm summer days.