FYI (updated (again)):
A 5x5' cube of water weighs 3538 kg, or 3.9 tons
A 5x5' cube of ice weighs 3243kg, or 3.6 tons.

The Ice Cube would have 13AC and have 18(4d8) hit points (per DMG).
Note: I personally would add a damage threshold for bludgeoning damage equal to the proficiency modifier of the caster.

Calculating Damage
Don't sacrifice fun for realism. Use the trap rules.

Math:
1x1x1' of water  = 62.4 lbs = 28.3kg
62.4lbs x 125 = 7800 lbs = 3538kg = 3.9 tons

1x1x1' of ice = 57.2 lbs = 25.9kg
57.2lbs x 125 = 7150 lbs = 3243kg = 3.6 tons

Okay, so 5ft cube, means it has to stay in the 5ft cube correct? Can't be, say 125ft of water now on the ground frozen? And 2 non instantaneous effects, means only possibly 2 frozen 5ft cubes, or... Okay, what does everyone else do with this spell. Right now for me, its a 2 frozen 5ft cubes acting as a wall of sorts. Earlier was 5 1ft water fishes dancing around. I know its DMs discretion. But yeah. Clarification please. 

a 5 foot cube of water weighs 3 and a half tonne my friend.

Think of it - a 1m x 1m x 1m cube of water is a tonne, so a cube with 5" sides couldn't possibly weigh less.

Quote from belfastbiker >>

a 5 foot cube of water weighs 3 and a half tonne my friend.

Think of it - a 1m x 1m x 1m cube of water is a tonne, so a cube with 5" sides couldn't possibly weigh less.

 Good call! The web calculator I used was definitely busted and I didn't check the math. Though my rough manual re-calculation gave me 3086 lbs for 5x5 cube of ice, or 1.4 metric tons.

(5" is 5 stupid inches, btw)

Could you shape the water in a way to create an air bubble so you can breathe while you swim? And can you move it with you as you swim? How would that work in and out of combat?

As written: If you cast this spell multiple times, you can have no more than two of its non-instantaneous effects active at a time... so:

1) You cause the water to form into simple shapes and animate at your direction. This change lasts for 1 hour.
2) You freeze the water, provided that there are no creatures in it. The water unfreezes in 1 hour.

and

You instantaneously move or otherwise change the flow of the water as you direct, up to 5 feet in any direction. This movement doesn’t have enough force to cause damage.

You can form the water to a shape, make it into ice, and then move it. All at the same time.
What exactly is the definition of a simple shape ?

Is a rough humanoid shape (two arms, two legs, a body) simple?   
Is a 5' diameter amoeba a simple shape?  

Is a hollow sphere simple ? (a hollow, watertight sphere of ice that stays frozen for an hour, filled with air, and moving underwater like a submarine)

Fun fact the average humanoid is 80% water you know what that means

you should be able to breathe underwater and air 

2 5' cubes of water could dam a stream and could make a cool damaging trap

>You can form the water to a shape, make it into ice, and then move it. All at the same time.

Not by RAW: "You manipulate it in one of the following ways:" 1 way per casting; 1 Action per casting; 3 Actions to do the above, over 3 rounds.

Would it be possible to have it shaped and then freeze the shape?

So me saying this doesn't negate the rule of cool... it's your world, let spells do whatever you want them to.

BUT...

Things this spell cannot do RAW -

1. Make water float.
2. Raise a wall of water into the air.
3. Make an ice wall. (This isn't Shape the Flowing River)
4. Turn water into mist / mist into water.
5. Control the water inside of someone's body.
6. Part the water in a flowing stream.

This spell is not Wall of Water/Ice or Control Water, nor is it Watery Sphere (which actually specifies that the water floats).  Context of spells is important.  Clues as to how other spells are written help you understand how all spells are intended.

Gravity is still a constant throughout this spell, you can make water do a lot of stuff, but within reason.

• Can you flow water out of your water skin?  Yes. 
• Can you make it act like a water gun? Yes. 
• Can you freeze that water gun in the middle of the air? Yes.  
• Can you cause beads of water on something to move around and spell something?  Yes.
• Can you make a wave while in water? A small one, likely, yes.
• Could this spell stop rain from falling on you? Yes. Also if you were wet this spell could dry you off.
• Could this spell open a path through a waterfall? Yes, as long as the force of the waterfall wouldn't originally cause you to take damage.

This single cantrip does not turn you into a water bender.

ur a god thxs

I feel like an ice wall isn't out of the question? like assuming gravity is the issue there let's say you do like a ramp and freeze type of thing make the water move forward and freeze at it goes it's not a straight-up wall but still cover (and if I didn't explain it well enough basically make a wave then freeze. you said it doesn't make you a water bender but for the sake of example i think there's a part in avater that basiclly looks like this) 

5' by 5' is 25 cubic feet. This spell only allows you to control 1/5 of that, 5 cubic feet. 1.7 cubed, or a little under 2' cubed is the maximum amount of water you can control

I like this spell, but what I like (creative freedom) also means "must ask your GM for all creative uses."  

Can you make a water "halo" that looks cool and floats?  Or does the "shape" that defies gravity still have to touch the ground?  I would assume you cannot form a "bubble helmet" under water because it "doesn't have enough force" to hold back heavy water but that's still a GM call.  

Can you cover yourself with red water and look like you're a blood-soaked crazy person right before you make your intimidate check with advantage?  Can you lift a big block of water over someone's head and turn it into ice?  Can you fill a lock with water, then freeze it solid and burst the lock like in this clip? https://www.youtube.com/watch?v=9HjHG8InQ-8  

Personally, I assume "any direction" includes up, but if you want to keep it 'floating' you have to keep casting the spell.  Instead of normal concentration you have "concentration +" which also costs you your standard action each round.  Further while you can move the water or make it float my own presumptive ruling is that the water would move rather slowly and without stability.  You could lift a blob of water with a floating toy boat because it's light enough, but a rowboat would capsize and sink through the blob.  A tiny person MIGHT be able to be lifted or even fly with it (assuming they have enough bouyancy) but they'd risk falling out and a number of other issues.  And they'd have to be flipping TINY.  

Quote from Xavia11 >>

5' by 5' is 25 cubic feet. This spell only allows you to control 1/5 of that, 5 cubic feet. 1.7 cubed, or a little under 2' cubed is the maximum amount of water you can control

 No, the spell as written says a 5 foot cube, not 5 cubic feet. You can control 25 cubic feet of water.

Technically 125 cubic feet, since it's 5x5x5.

Technically it's 125 cubic feet, since it's 5x5x5.

Says fits in 5 foot cube that means five foot cube