An apparatus for protecting and providing user access to a touch sensitive device (1, 10) underwater, comprising: a waterproof casing comprising an inner cavity configured to receive the touch sensitive device (1, 10), the casing comprising: a first area of the casing for providing user access to the touch sensitive device; and a transparent first membrane arranged to cover at least part of the first area of the casing; the inner cavity being configured to receive the touch sensitive device (1, 10) so that a user interface of the touch sensitive device is arranged adjacent to the first membrane of the first area; the first membrane being flexible and configured to allow a user to bend the first membrane by pressing with a finger or some other touch element for using the touch sensitive device (1, 10); characterized by: non-conductive and incompressible fluid being arranged to fill the inner cavity to provide a gap between the user interface of the touch sensitive device (1, 10) and the first membrane; a pressure control membrane arranged to cover at least part of a second area of the casing; wherein the fluid is in contact with both the first membrane and the pressure control membrane; the inner cavity is defined by the casing, the first membrane, and the pressure control membrane; and a pressure control element operationally connected to the pressure control membrane, the pressure control element being configured to flexibly bend the pressure control membrane to change pressure of the pressurized non-conductive fluid; wherein the fluid pressure is adjustable using the pressure control element and the pressure control membrane. a waterproof casing comprising an inner cavity configured to receive the touch sensitive device (1, 10), the casing comprising: a first area of the casing for providing user access to the touch sensitive device; and a transparent first membrane arranged to cover at least part of the first area of the casing; a first area of the casing for providing user access to the touch sensitive device; and a transparent first membrane arranged to cover at least part of the first area of the casing; the inner cavity being configured to receive the touch sensitive device (1, 10) so that a user interface of the touch sensitive device is arranged adjacent to the first membrane of the first area; the first membrane being flexible and configured to allow a user to bend the first membrane by pressing with a finger or some other touch element for using the touch sensitive device (1, 10); characterized by: non-conductive and incompressible fluid being arranged to fill the inner cavity to provide a gap between the user interface of the touch sensitive device (1, 10) and the first membrane; a pressure control membrane arranged to cover at least part of a second area of the casing; wherein the fluid is in contact with both the first membrane and the pressure control membrane; the inner cavity is defined by the casing, the first membrane, and the pressure control membrane; and a pressure control element operationally connected to the pressure control membrane, the pressure control element being configured to flexibly bend the pressure control membrane to change pressure of the pressurized non-conductive fluid; wherein the fluid pressure is adjustable using the pressure control element and the pressure control membrane. non-conductive and incompressible fluid being arranged to fill the inner cavity to provide a gap between the user interface of the touch sensitive device (1, 10) and the first membrane; a pressure control membrane arranged to cover at least part of a second area of the casing; wherein the fluid is in contact with both the first membrane and the pressure control membrane; the inner cavity is defined by the casing, the first membrane, and the pressure control membrane; and a pressure control element operationally connected to the pressure control membrane, the pressure control element being configured to flexibly bend the pressure control membrane to change pressure of the pressurized non-conductive fluid; wherein the fluid pressure is adjustable using the pressure control element and the pressure control membrane.