US Geological Survey
Usgs: Bathymetry of the Marshall Islands
This map details the area around the Marshall Island seamounts. Seamounts are one of many features that are found in conjunction with abyssal plains.
CK-12 Foundation
Ck 12: Earth Science: Bathymetric Evidence for Seafloor Spreading
[Free Registration/Login may be required to access all resource tools.] Describes features of the seafloor and how they are mapped by echo sounding. It touches upon the continental margin as well.
Institute of Marine Science
Forsea: If I Can't See It, How Do I Know It's There?
A diagram showing features of the seafloor and a laboratory experiment involving a model of the seafloor highlight this site. This is a good resource for teachers as well.