Water goes up in plants by cappilary action. So that should also explain water inside coconuts.
My doubt relates to the easy experiment of transfering water from a filled glass to an empty one using some chord or even a toilet paper pressed as a chord.
Even if the paper is initially dry, water is gradually transferred until levels are equal at both glasses.
But it is not possible (at least I couldn't make happen) to transfer any drop of water to an empty glass whose bottom is above the water level of the filled glass.
So how is it possible for a coconut? Maybe its internal pressure is below atmospheric?
I know there are other similar questions, but the answers tends to follow the capillarity action (what is obvious to me, but seems incomplete), or postulates great negative pressures. (But if it is 1 atm outside, at most it should be zero inside, and a perfect vaccum inside plants is too strange).
But there is maybe some combined effect of capillarity and negative pressure that is not well discussed so far.