Friends of V.I. National Park seminars run January through April. Call 779-4940 to make your reservation. Explore the island's marine eco-systems about the catamaran Jolly Mon on the April 2 Marine Biology Sailing Trip. Park rangers Carrie Stengle and Rob Waara will lead the way at two to three snorkeling spots. It runs from 9 a.m. to 4 p.m. Meet at the park Visitor's Center dock with sunscreen, water and lunch. The fee is $70 for non-members and $60 for members.