Bob has described the entrance as follows:-
"In approaching Port Jefferson from any direction, it is wise to keep
offshore
and watch the chart carefully, as there are outlying rocks and shouls The
entrance is narrow and there is apt to be a strong tidal current in or out.
An
experienced cruising man warns that:
Sometimes a really dangerous sea makes up outside and between the jetties on
the ebb tide. Entering is possible at all times, providing some care is
taken.
Another experienced cruiser feels this is too strong a statement. Suffice it
to
say, treat it with respect."

I have that cruising guide. It is not just "LIS" but rather all of New
England, and while venerable and charming and informative about shopping in
port, it is not very good for navigation. It has no chartlets in it and
information often is inconsistent with reality. I am amazed that anyone would
set out for an unfamiliar port armed only with it and without proper charts. A
copy of Eldridge would also be wise to predict the current and tide not only
for that inlet, but also to take advantage of (or avoid) the currents available
along that entire trip.