Amphibious vehicle comprising: - at least one shell having a prow, said prow being ended with a bow, - a device for confining an air chamber under the vehicle comprising at least one flexible sleeve, said flexible sleeve having: • at least one portion, called prow portion, located at the prow of said shell, • a first edge, called upper edge, • a second edge, called lower edge, separate from said upper edge, - a device for deploying said flexible sleeve, characterised in that said device for deploying said flexible sleeve: • comprises at least one rigid retention bar, to which is at least partially fixed the lower edge of said prow portion, • is adapted to be able to move at least the lower edge of said prow portion under the bow between: ❖ a deployed position of said flexible sleeve, wherein said lower edge is located lower than said upper edge, so as to make it possible for an inflation of said flexible sleeve making it possible to confine at least one air chamber under the vehicle, and ❖ a raised position of said flexible sleeve, wherein said lower edge is above a floating line of the shell so as to make it possible for said shell to ensure one single floating of the vehicle on the water, without confining the air chamber under the vehicle by said flexible sleeve. - at least one shell having a prow, said prow being ended with a bow, - a device for confining an air chamber under the vehicle comprising at least one flexible sleeve, said flexible sleeve having: • at least one portion, called prow portion, located at the prow of said shell, • a first edge, called upper edge, • a second edge, called lower edge, separate from said upper edge, • at least one portion, called prow portion, located at the prow of said shell, • a first edge, called upper edge, • a second edge, called lower edge, separate from said upper edge, - a device for deploying said flexible sleeve, characterised in that said device for deploying said flexible sleeve: • comprises at least one rigid retention bar, to which is at least partially fixed the lower edge of said prow portion, • is adapted to be able to move at least the lower edge of said prow portion under the bow between: ❖ a deployed position of said flexible sleeve, wherein said lower edge is located lower than said upper edge, so as to make it possible for an inflation of said flexible sleeve making it possible to confine at least one air chamber under the vehicle, and ❖ a raised position of said flexible sleeve, wherein said lower edge is above a floating line of the shell so as to make it possible for said shell to ensure one single floating of the vehicle on the water, without confining the air chamber under the vehicle by said flexible sleeve. • comprises at least one rigid retention bar, to which is at least partially fixed the lower edge of said prow portion, • is adapted to be able to move at least the lower edge of said prow portion under the bow between: ❖ a deployed position of said flexible sleeve, wherein said lower edge is located lower than said upper edge, so as to make it possible for an inflation of said flexible sleeve making it possible to confine at least one air chamber under the vehicle, and ❖ a raised position of said flexible sleeve, wherein said lower edge is above a floating line of the shell so as to make it possible for said shell to ensure one single floating of the vehicle on the water, without confining the air chamber under the vehicle by said flexible sleeve. ❖ a deployed position of said flexible sleeve, wherein said lower edge is located lower than said upper edge, so as to make it possible for an inflation of said flexible sleeve making it possible to confine at least one air chamber under the vehicle, and ❖ a raised position of said flexible sleeve, wherein said lower edge is above a floating line of the shell so as to make it possible for said shell to ensure one single floating of the vehicle on the water, without confining the air chamber under the vehicle by said flexible sleeve.