An apparatus for closing and sealing a vascular puncture is connected to an energy supply such that heat is generated in, or thermally conducted to, the tissue, thereby thermally fusing the vascular tissue together. The method for closing and sealing a vascular puncture comprises applying radio frequency or other energy to the tissue, the energy being sufficient to thermally fuse the tissue together, thus sealing the puncture. Embodiments of depth finding and guiding devices, as well as blood vessel occluders, are also disclosed.