SEAFLOOR PROFILING—Lesson #3: Understanding seafloor maps from the NWHI




Internet access (

(In the future there will be a more complete bathymetric map of the whole Northwestern Hawaiian Islands available on the website. However, for now, this lesson will be written with the use of the 2 bathymetric maps that are on the website currently.)


student handout, “SEAFLOOR PROFILING—Lesson #3: Understanding seafloor maps from the NWHI student handout”

paper & pencil


Procedure/Assessment for Lesson #3:

(1) President Clinton promulgated “Executive Order 13178—Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve” in the final days of his presidency, starting the process for the NWHI becoming the nation’s largest marine sanctuary. It became immediately apparent that one of the first research projects would be to accurately map the boundaries of this sanctuary. Once scientists have accurate maps, they can plot locations of various geological, hydrological and biological points of interest. Furthermore, mapping will help identify and protect the resources within the sanctuary’s boundaries.


The Reserve is using an up-to-date mapping method called “broad beam or multibeam” mapping. Earlier echolocation equipment sent just one sound beam to the seafloor right below the ship. Multibeam systems can send out a 100 beams, some going directly down to the seafloor, while others go out at an angle to the left or right of the ship. In this way, scientists can see a swath of the seafloor instead of only a single line profile.


(2) In this lesson, students will be able to apply their knowledge from Lessons 1 & 2 to understand how to read a real, oceanographic “broad beam, or multibeam” seafloor map from the Northwestern Hawaiian Islands. The minimum time needed would be part of a 45-minute period.


(3) If possible, have each student on a single computer; otherwise, have student partners or trios share one computer.


(4) Have students follow the directions to answer the questions on the “SEAFLOOR PROFILING—Lesson #3: Understanding seafloor maps from the NWHI student handout”