2.1.1 The hydrography of the NWHI underscores
the need for mariners to navigate with extreme caution. The chain
of small islands, atolls, banks, seamounts, pinnacles, shoals, and
other emergent features are remnants of volcanic islands which are
eroding and subsiding beneath the ocean surface. While only the peaks
of the original islands remain above the water’s surface, coral
growth on submerged slopes has matched the rate of subsidence (Evans et al. 2004). Due to these features, navigation in this area
is dangerous and must be done with extreme caution. Water depths in
this area range from the water’s surface to slightly submerged
banks, reefs, and other emergent features to the ocean floor at more
than 14,000 feet.
2.1.2 The area of the proposed PSSA is currently
covered by mostly small scale charts, with the most recent surveys
taking place since 2000 near known islands, reefs and atolls. Although
modern hydrographic surveys by the University of Hawaii and satellite
imagery of the area have allowed NOAA’s Office of Coast Survey
to correct the position of several of these features, many of the
submerged banks and isolated features have yet to be updated or discovered.
2.1.3 In 2003, a mapping expedition was undertaken
by NOAA and the University of Hawaii Undersea Research Laboratory.
The primary objective of this project was to provide for more complete
and accurate charts and survey data to support the management of the
NWHI Coral Reef Ecosystem Reserve and protection of its resources.
This expedition included hydrographic experts to ensure that appropriate
International Hydrographic Organization quality standards were met.
The hydrographic data will be applied to all affected charts by the
end of 2007. Notwithstanding, large areas of the NWHI remain to be
surveyed and nautical charts updated.