Several weeks ago I posted the following question:

"I have some NOS hydrographic data files that have been exported from
the
NOS Geodas application and are now in XYZ ASCII format.  Could anyone
tell me how to get these files into ArcView?  The import utilities in AV

3.2 aren't doing the trick; I tried importing them as ASCII Raster files

but end up with a GRID error dialog box.  Thanks for any help."

After some head scratching I came up with a solution and some additional
info:

National Ocean Service (NOS) provides coastal bathymetric data
(soundings) compiled from decades of hydrographic surveys.  When one
purchases these datasets NOS also provides GEODAS, an application that
allows the user to search among the numerous individual hydrographic
surveys, display the soundings data, and download in several formats.
One of these formats is xyz ASCII.

To bring the xyz ASCII file into ArcView:
1) import into a spreadsheet program such as Excel as space delimited
2) save as a *.txt file
3) add this table to ArcView
4) select Add Event Theme, and use the *.txt file
5) if the soundings are dense enough in the area of interest a grid may
be interpolated from the shapefile

I also learned that NOAA is working on providing gridded bathymetric
datasets for coastal US water.  Gridded datasets for the NE coastlines
are already available; the remaining east coast will be available
shortly; Gulf of Mexico datasets coming this summer; west coast perhaps
by late summer or fall; Alaska coming in after that.

This is the address of the National Geophysical Data Center that sells
these datasets.  Descriptions and prices and ordering info is provided.

http://www.ngdc.noaa.gov/mgg/announcements/products.html#93-MGG-01


I did receive one reply from list participant Michael Kohler, which
essentially parallels my explanation above:
"I do this all the time for a back drop of bathymetry for work. The xyz
files
need to be comma delimited first. I do this in excel. Then import the
data
into arcview by using the add table method. Select the txt files opiion
and
this will make a table. Then add the data to a view as an event theme.
Then
use the convert to shapefile option to make the final shapefile of the
data
points. I usually make a grid and then contour it to get my final data."