Huna is a Hawaiian word meaning secret, but it also refers to the esoteric wisdom of Polynesia. Kupua is another Hawaiian word and it refers to a specialized healer who works with the powers of the mind and the forces of nature. In that respect it is very similar to the Siberian Tungusic word shaman.

The understanding of Huna described here comes from the kupua family Kahili from the island of Kauai, through Serge Kahili King, an adopted grandson of that family who was trained in the kupua tradition.

The Seven Principles
The basic assumptions of Huna are these:

1. The World Is What You Think It Is.
2. There are no limits.
3. Energy Flows Where Attention Goes.
4. Now Is The Moment Of Power.
5. To Love Is To Be Happy With
6. All Power Comes From Within.
7. Effectiveness Is The Measure Of Truth.

The Three Selves (or Four)
Another set of assumptions used in Huna is that human behavior and experience can be explained and changed through the interaction of three (sometimes four) selves, aspects or functions:

1. The High Self (Kane, Aumakua, Spiritual Mind), has the function of creativity, is motivated by harmony, and uses energy.

2. The Conscious Self (Lono) has the function of reasoning, is motivated by power, and uses imagination.

3. The Subconscious Self (Ku) has the function of memory, is motivated by happiness, and uses sensation.

4. The Core Self (Kanaloa) has the function of will, is motivated by experience, and uses confidence.

The Four Levels of Reality
A third set of assumptions coming from the kupua tradition divides all experience into four levels or frameworks of beliefs about reality which can be summarized as follows:

1. Everything is objective.
2. Everything is subjective.
3. Everything is symbolic.
4. Everything is holistic.

It has recently become fashionable to try discredit the word "huna". Some say the word is a non-Hawaiian invention by Max Freedom Long. Others say the word was never used as a part of the Hawaiian esoteric tradition.
    For a more thoughtful view check out
     Huna and Hawaiians  by Serge King.

"Many shamans play a game of developing power and insight through conflict and control of personified things (the so-called way of the warrior). Other shamans act as if power and insight can best be achieved through love and cooperation. These shamans de-personify things and work with the effects of things and conditions (what I call the way of harmony.)"
— From  What is a Shaman?  by Larry Williamson
Dr. King calls the way of harmony, "the way of the adventurer".

"I have often read that a kahuna is a Hawaiian shaman. There are and were kahuna shamans, but they are two distinct traditions. There were Druids also that were shamans, but in both cases they were rare. And, as might be guessed, there were (and are) shamans in Polynesia and Celtic areas that are not kahuna or druids. A shaman is a healer but there are few shamans among healers; today and even in the distant past.
Collections of ideas like huna, or whatever anyone wants to call the Hawaiian esoteric tradition, have shamanistic ideas, but like similar traditions around the world, are not shamanism."
— From  What is a Shaman?  by Larry Williamson
Note that Dr. King's article above uses the word "huna" several times. But, the "Seven Principles", especially number 7, leads to a kupua path. Note the title of his article is "What is Huna Kupua?" not "What is Huna?"

There is no single esoteric tradition in Hawaii. The beliefs and values of the Hawaiians of the past differed from island to island and from family to family. There are common threads of thought weaving through these traditions, but there are differences in details and even basic ideas – The Hawaiians were a very individualistic society.