function [newmsk] = findocean( oldmsk, nstartpts, periodic );

[nx ny]=size(oldmsk);
if periodic
 xp=[2:nx 1];
 xm=[nx 1:nx-1];
 yp=[2:ny ny];
 ym=[1 1:ny-1];
else
 xp=[2:nx nx];
 xm=[1 1:nx-1];
 yp=[2:ny ny];
 ym=[1 1:ny-1];
end

msk=0*oldmsk;
i=0;
npts=nstartpts;
for k=1:floor(ny/npts):ny;
 for j=1:floor(nx/npts):nx;
  if oldmsk(j,k)==1
   i=i+1;
   msk(j,k)=i;
  end
 end;
end;

nmsk=i;

nnz=size(find(msk==0),1);
nnzo=nnz+1;
nnzoo=nnzo+1;

iter=0;
while nnz ~= nnzoo & iter < max(nx,ny)/npts

 nnzoo=nnzo;
 nnzo=nnz;

 iter=iter+1;
 disp( sprintf('Findocean: iter=%i, num. points in ocean=%i',iter,nnz) );
 pcol(sq(msk)'); drawnow;
% Loop over all masks values
k=1;
while k<=nmsk

% Procreate right
  ii=find(msk(xm,:)==k & msk==0 & oldmsk==1);
  msk(ii)=k;
  ii=find(msk(xm,:)==k & msk==0 & oldmsk==1);
  msk(ii)=k;
  ii=find(msk(xm,:)==k & msk==0 & oldmsk==1);
  msk(ii)=k;
% Procreate up
  ii=find(msk(:,ym)==k & msk==0 & oldmsk==1);
  msk(ii)=k;
  ii=find(msk(:,ym)==k & msk==0 & oldmsk==1);
  msk(ii)=k;
  ii=find(msk(:,ym)==k & msk==0 & oldmsk==1);
  msk(ii)=k;
% Procreate left
  ii=find(msk(xp,:)==k & msk==0 & oldmsk==1);
  msk(ii)=k;
  ii=find(msk(xp,:)==k & msk==0 & oldmsk==1);
  msk(ii)=k;
  ii=find(msk(xp,:)==k & msk==0 & oldmsk==1);
  msk(ii)=k;
% Procreate down
  ii=find(msk(:,yp)==k & msk==0 & oldmsk==1);
  msk(ii)=k;
  ii=find(msk(:,yp)==k & msk==0 & oldmsk==1);
  msk(ii)=k;
  ii=find(msk(:,yp)==k & msk==0 & oldmsk==1);
  msk(ii)=k;
  
  for j=1:nmsk;
    if k~=j
% Join left
      ii=find(msk(xm,:)==j & msk==k);
      if ~isempty(ii)
        msk(find(msk==j))=k;
      end
% Join down
      ii=find(msk(:,ym)==j & msk==k);
      if ~isempty(ii)
        msk(find(msk==j))=k;
      end
    end
  end

  k=k+1;
end

nnz=size(find(msk==0),1);
end % while

% Find largest patch
for k=1:nmsk;
  np(k)=prod(size(find(msk==k)));
end
[NP,I]=sort(np);

disp('Number of points in each region:')
disp( sprintf('%7i',NP') );

newmsk=0*msk;
newmsk( find(msk==I(end)) )=1;
if NP(end-1) > NP(end)/4
  newmsk( find(msk==I(end-1)) )=1;
end