Guadeloupe. Grande Terre low The Grande Terre portion of Guadeloupe is larger than the mountainous Basse Terre part, from which it is sepa- rated by broad mangrove swamps. Through these flows back and forth with the tide, the brackish arm of the sea called the Rivière Salée, freshened by the rivers flowing constantly from them from the mountains of Basse Terre and during the rainy season from the flat surface of Grande Terre as well. 8 A slight current sets through the river.