Zorgon is correct. Solid ice sits on? -yes sea water. It is heavier than fresh water and sea water doesn't freeze. Admiral Byrd had his experience at the south pole not the North and spoke of land with valleys and greenery. Not a hole.
There are shapes such as your north pole pic in GE over my daughters school less than a kilometre away from my house which is very clear. I have been to her school many times and they are hiding nothing. GE pics are taken within the last 2-3 years and are not in real time. The PTB does however have the ability to view in real time.
This post is for those that wonder about this hollow earth thing,not those who have already made their minds up and do not wish to be bothered with facts.
There's the mass to consider,the iron core and all sorts of other technical stuff. The earth is a giant electric motor,hence why we have magnetic poles and weather with lightning, the van allen belts, why Tessla's 8cycles per second free energy works and lots of other technical stuff.
Phil Schneiders vid is interesting however. He says he worked in DUMBS (Deep Underground Military Bases)(let's get it right) all over the USA. More than 130. Claims to have had a shootout with aliens living underground. He died in very suspect circumstances-ruled suicide after giving more than 30 lectures exposing the black projects he worked on.
Check that out - it has far more cred than the hollow earth theory.

Can I change it to hollow head theory

You have great researching skills Kathy- please don't waste them on this.
Many adventurers go to both poles including my fellow NZers whose books I have read. The authorities are concerned about the saftey of such people-read 'we don't want to foot the bill for your rescue so put money up front or we won't approve'. And the rescue personell risk their own lives when the adventurer screws up or can't hack it. Fair enough too I say. It is very expensive to mount a rescue to either pole. There is no food there or anything but snow and rocks and ice and extreme cold. Humans have no business going there,nor peaking Everest or K2 or the middle of a desert. Steve Fosset planned and paid for his adventures. Other people go caving.
There are huge cave systems known and unknown so yes, there are pockets of 'hollow earth' all over the planet.
Secret Nazi bases at the South pole are being talked about. There could be something in it!
Aliens and ships from other stars and dimensions I say yes very definately, just not that we live on a hollow sphere.