St Croix River, 121 km long, rises in the Chiputneticook Lakes and flows SE to Passamaquoddy Bay, forming part of the border between NB and Maine. It was discovered (1604) by the French, and de MONTS built the first settlement in Acadia on Ile Sainte-Croix (now St Croix I) near the river's mouth.

The site was chosen for its central position, good anchorage and ease of defence. However, the winter was cruel; there was no fresh water or firewood on the island. Of the 80 colonists, 36 died of SCURVY. The next summer the houses were dismantled and moved to PORT-ROYAL, a more salubrious spot across the Bay of FUNDY. The river was to serve as part of the boundary between British territory and the US, but its location was in dispute until an excavation found the remains of de Monts's camp and conclusively identified the river (1797).