The best photographs, and indeed the best pieces of visual art in general, are to me either emotionally overwhelming or not self-evident.  The former is pretty self-explanatory, and probably includes the greatest photojournalism images.  It is harder to define the latter, because I started with a negative.  An affirmative definition - for example, "mysterious," "ambiguous," "intriguing" - would be too under-inclusive or superficial.  Better to start with a bigger tent: "not self-evident."  It is too hard to explain the contours of that notion with any precision, but that phrase at least starts the conversation.  It implies there may be something going on beyond the obvious.  

A nice photograph doesn't need to be "not self-evident," but a nice photograph rarely rises beyond niceness; calendar/poster art is usually nice or very nice.  And it usually makes us feel good by association: we wish we could have been where the photograph was taken when it was taken.  But it isn't going to provoke us with very many questions.  

That said, these images aren't among the "best" of photography.  They are too evident and self-explanatory.  There is no significant mystery (apart from the inherent mystery in any totem pole).  But they are illustrations of places and things and activities that help us consider the world at large.  If you spend most of your time in an office, you may not see a seiner retrieving its seine net; you may not have watched the graphic patterns in an island's reflections in the wake of a working boat.  These are, both in the best sense and the worst sense, "nice" photographs.

Patterns in the wake of M/V Retriever

Sky reflections

Extra bow watch in Peril Straits

Sunrise

Memento retrieves its seine.

Reflections on placid waters

Shore

Totem. These images are not self-evident.

Forest path through tall trees