Systems and methods for compensating for compressibility and thermal expansion coefficient mismatch in buoyancy controlled or buoyancy-driven underwater vehicles are disclosed herein. An underwater vehicle configured in accordance with one embodiment of the disclosure, for example, can include a hull and a compartment carried by the hull and at least partially flooded with a first liquid having similar properties as a surrounding liquid into which the hull is configured to be deployed. The first liquid has a first compressibility and thermal expansion coefficient. The underwater vehicle can further include a compressibility and thermal expansion coefficient compensation system comprising a container filled or at least partially filled with a compressible liquid comprising silicone in the compartment. The compressible liquid has a second compressibility higher than the first compressibility and second thermal expansion coefficient higher than the first thermal expansion coefficient. The compressible liquid can include, for example, hexamethyldisiloxane (HMDS).