Studying or Internship
If you are going abroad specifically for study purposes, then your Dutch health insurance generally just continues. This allows you to remain insured for medical expenses through your Dutch health insurance.
Moreover, It is also advisable ,prior to your departure, to find out whether an additional supplementary health insurance, and travel insurance, is desired. This partly depends on your personal situation and the duration of your stay abroad.
Are you going abroad because of an internship, and will you receive compensation for your work? In that case, you are generally insured in the country where you will do the internship.