Abstract: A planter for retaining gravel and landscaping effects in underwater settings such as an aquarium is disclosed. The invention comprises a plurality of retaining walls disposed in an upstanding spaced apart relationship for forming a plurality of landscaping sections with each section having a different height from every other section for defining a terrace relationship with the adjacent retaining walls. A plurality of elongated spacers are disposed in paired releasable communication with the retaining walls for maintaining the spaced apart relationship between the adjacent retaining walls. Each retaining wall further has a plurality of apertures adapted for urging water flow from one landscaping section to the next lowermost adjacent landscaping section, and a second plurality of apertures adapted for urging cooperative engagement between adjacent elongated spacers.