Double network (DN) hydrogels made with two covalent networks in the classic J.-P. Gong manner can be remarkably tough but, as this toughness has its origin in breaking covalent bonds, they are unlikely to be fatigue resistant and also are difficult to make. Gels made with the tight network formed by ionic crosslinking make an interesting comparison as they are much easier to make and can be even tougher.  I will present recent work comparing the mechanical properties of the two systems.