He first attacked and captured the island of Santa Catarina (Catalina) located about 50 leagues off the coast of Honduras. At Santa Catarina, he built fortifications and planned to turn it into a permanent base of operation. While there, he was successful in attacking the settlements on Tierra Firme, and capturing several Galleons leaving Panama with their cargos of treasure. While there, he proposed to the governor of Jamaica, that the make the island a separate country, for the buccaneers. He suggested that they send diplomatic representatives to the different courts in Europe.

Threatened with a mutiny by his captain, that upset with the lack of movement and treasure, he agreed to go after the big prize in 1666. He left a small contingent of men at Santa Catarina to protect it.  His men landed off the coast of Boca's del Toro, and proceeded overland to Natá. They had no idea what was ahead of them when they landed in Veraguas. The jungle and wild animals (insects and reptiles) took its toll on his men. If it had not been of the Indians, that were more then willing to help the buccaneers against the Spanish, they would not have made it.

When the reached Natá, they found that the town was well defended, and had to retreat after suffering serious losses. Leaving the area without any booty, he tried to attack the capital of Costa Rica, Cartago. By the time they reached Cartago, they were in very bad shape. The journey was hard, and some of the men were wounded at Natá. Food was not as plentiful as they expected, and the men were staving by the time they got there. At Cartago, they were again defeated, and had to retreat back to Santa Catarina.  He then returned to Santa Catarina, where he sent letters to the governors of Jamaica and Tortuga, requesting help in attacking Cartago again; but, they refused to help and Mansveldt died soon after, leaving Henry Morgan in command of his navy.