A splash guard for a snorkel tube has an extension pipe, a pivot member pivotally mounted on the extension pipe, a space surrounded by the extension pipe and the pivot member, a float member pivotally mounted on the pivot member and located in the space, a closure member disposed on the pivot member, and a cover disposed on the extension pipe. The extension pipe has a first aperture and a second aperture in opposition. The pivot member has two pivot arms and a support portion. A pivoting limit is formed in a surface of the support portion facing the extension pipe which is selectively abutted by the float member. The closure member selectively seals the first aperture. The cover has a socket selectively engaged by the projection. The present invention can prevent inadequate sealing and has the advantages of light weight and small volume.