In the late afternoon, the riders will compete in the third stage, a 6.3km time trial through the streets of Rotterdam.
Belgian rider Audrey De Keersmaeker attacked early on this 67km ride from Dordrecht to Rotterdam, which saw numerous crashes.
But it was Kool who consolidated her yellow jersey by overtaking compatriots Lorena Wiebes, the pre-race favourite who was hoping to make up for a problem with her chain on Sunday, and Marianne Vos in the sprint up the final straight.
"I had to stay calm because it was very edgy," explained the DSM sprinter.
"I'm feeling strong, whereas two weeks ago I wasn't feeling well. To win with the yellow jersey is just extraordinary."
The race enters Belgium on Wednesday and finishes on Sunday with one of cycling's most challenging climbs up Alpe d'Huez.
