In this study, palmyra palm leaf stalk fiber after silane treatment, E-glass, and organically modified nanoclay were used as reinforcement in an unsaturated polyester matrix. Bilayer and trilayer patterns were used to fabricate the composites. The composites were exposed to moisture (seawater) and their behavior (after 3 days of exposure) before and after moisture absorption, in terms of mechanical properties (tensile, flexural, and impact), was determined as per ASTM standards. Their acoustic response and thermal behavior were also tested. A steady moisture absorbance behavior was noticed and the composites were found to saturate after 21 days of exposure. The mechanical response and thermal stability were found to be improved due to hybridization of the glass fiber, silane treatment, and the use of nanoclay. X-ray diffraction and scanning electron microscopy were used to determine the crystallinity index and mechanism of fracture of the composites, respectively. © 2023 Elsevier B.V., All rights reserved.