For certain countries, a visa requirement applies, to be admitted to St.Maarten. Are you required to have a visa? Then you must apply for a visa before traveling to St.Maarten. For more information about the Caribbean visa or how to apply for it, you can find more details via https://www.nederlandwereldwijd.nl/caribisch-visum/visum-nodig
As Sint Maarten is a constituent country of the Kingdom of the Netherlands, and visas are a Kingdom affair, they are not individually processed and provided by the constituent countries. Please refer to the information below from the Government of the Netherlands for more information on Caribbean Visa Application.
Short Stay (Less than 90 days):
https://www.nederlandwereldwijd.nl/caribisch-visum/kort-verblijf
Long stay (More than 90 days):
https://www.nederlandwereldwijd.nl/caribisch-visum/lang-verblijf-verblijfsvergunning