A hydration system includes first and second opposing flexible walls that form a bladder having a sealable compartment for containing a liquid. The system includes a drinking tube having a first end with a valve and a second end. A first port is configured to receive pressurizing gasses into the compartment. A second port is configured to provide fluid communication between the compartment and the drinking tube. The third port allows liquid to be supplied into the compartment. A first baffle and a second baffle connect the opposing walls within the compartment. The first and second baffles are configured to oppose expansion of the bladder as the pressurizing gasses are introduced into the compartment. A space between the first and second baffles is accessible via the third port. The space is configured to receive and secure a thermal pack. The thermal pack is insertable and removable via the third port. When sealed and pressurized, activation of the valve unseals the compartment and allows the liquid to be expelled from the compartment via the second port and the drinking tube as a result of a pressurization of the compartment by the pressurizing gasses.