Here is a rational description for you.
DMT with closed eye's is like watching the back of your eyelids light up into the most amazing colors and patterns you've ever seen promptly to give way to a dream like vision that can feel real/unreal to various degrees. On large doses complete loss of body sensation is achieved, loss of breath awareness can happen. Most people panik a little the first time this happens.
DMT with open eyes is like watching every object in the room jump into motion while color trails grow bolder in color and eventually fill the room until eventually you arrive in completely different world that may or may not be anything like the place you were moments ago. On large doses ego loss, and death/rebirth are often experienced.
Beyond that, pretty much anything you can possible imagine and more is possible. It's utterly different for every person that tries it. It can be the most amazing experience of a persons life or the most terrifying of a persons life.
To be honest I feel pretty comfortable saying that anyone who has not experienced a break through dose most likely has zero understanding about their real nature. The reason I can say that is a large dose strips away everything that you call you. Your like dislikes, your beliefs/unbeliefs, fears/concerns/anxieties/joys, everything that you think of as you is stripped away, but you are still there calmly aware. If you get lucky and get a white light dose you can literally feel this (I don't think it's yours) awareness grow to consume everything and merge with unity.
But seriously what I just wrote is meaningless in comparison.
Peace