Diving beetles are generally aquatic and live submerged in water during larval and adult stages. A few groupshave colonised hygropetric habitats and fewer species still can possibly be referred to as terrestrial. Here wedescribe six new Copelatine species that were mainly found in dry shallow forest floor depressions in the easternand northeastern lowland humid forests of Madagascar. Three new species are described in each of thetwo genera Copelatus and Madaglymbus: Copelatus amphibius sp. nov., Copelatus betampona sp. nov., Copelatuszanatanensis sp. nov., Madaglymbus kelimaso sp. nov., Madaglymbus menalamba sp. nov., and Madaglymbussemifactus sp. nov. Diagnosis, description, known distribution, ecology, and conservation notes areprovided for each species. All species are illustrated with a dorsal habitus image, ventral and lateral views ofthe male penis, and parameres. Photographs of the unusual terrestrial habitats where the species were foundare provided. Madaglymbus menalamba sp. nov. is also documented with macrophotos and videorecordingsof the terrestrial locomotion and behaviour in the field. Although these species should not be classified asterrestrial, or even semi-terrestrial Dytiscidae, they seem to be specialists of very ephemeral aquatic habitatsand stay put instead of disperse when the habitat dries up. It is hypothesised that this lifestyle and behaviouron Madagascar is restricted to the high-precipitation humid forest regions mainly in the east. It may alsorepresent a transition step, or stepping-stone, towards becoming fully terrestrial, a step that the few knownterrestrial Dytiscid taxa once passed through. It is very likely that this type of habitat is overlooked for aquaticbeetles, not only in Madagascar, and the six species herein described may be just the “tip of the iceberg”.