Nicheless lighting assemblies principally for swimming pools and spas are detailed. The lighting assemblies include features configured to dissipate heat. The assemblies additionally are designed to reduce possibility of water intrusion. Some versions of the assemblies may include thermally-conductive plastic overmolded onto at least one of a lens or a heat spreader. Versions of the assemblies additionally or alternatively may include a generally annular heat sink to which a printed circuit board containing at least one light-emitting diode (LED) is attached. Versions of the assemblies may be divided into subassemblies, one subassembly fitting into another, or include protective covers.