function check_locations(cruiseid)

%%%%%%%%%%% CMDR read cruiseid if we can
if nargin==0, cruiseid=getcruiseid; end;
if isempty(cruiseid), cruiseid=getcruiseid; end;
%%%%%%%%%%%

% Retrieve the necessary preferences for this cruise
group = group_name(cruiseid);

% cruise_dir is the main calibration data directory 
if ispref(group,'cal_data_dir')
   cruise_dir=getpref(group,'cal_data_dir');
else
   error(['The cal_data_dir preference was not set for cruise: '  ...
   	cruiseid '.  Run register_cruise.m']);
end

% Load data from the cruise database
db_file = fullfile(cruise_dir,[cruiseid '_db.mat']);
if exist(db_file)==2
   load(db_file);
else
   error(['The cruise data base file was not found on the path.  '  ...
   	db_file]);
end

% Check for the necessary variables in the cruise database.
n=who('btl');
if isempty(n)==1
   error(['btl variable not found in the cruise database. Run load_btl.m ']);
   return;
end

m_proj('Mercator','longitudes',[-85 -60] ...
,'latitudes',[15 32])
m_gshhs_h('patch',[.0 0.4 .0]);
m_grid
hold on
sta=vertcat(btl.station);
lon_sta=vertcat(btl.lon);
lat_sta=vertcat(btl.lat);
m_text(lon_sta,lat_sta,num2str(sta));