You need an embassy visa for Saint Barthélemy if you have a Saint Lucian passport
Visa options for Saint Barthélemy
Visitor visa is required for trips longer than 15 days
Travelers need a visa to visit Saint Barthelemy for Business or Tourism for more than 15 days. Travelers do not need a visa if staying for 15 days or less, with a limit of 120 days over 12 months. A paper or embassy visa is the only visa available for travelers visiting Saint Barthelemy for more than 15 days. The visa is typically a stamp or sticker added to the passport. Travelers must obtain this visa from a local embassy, consulate or visa center before traveling.
This is not offered by sherpa°.
Apply on the government site.