I think Shape Water will still work to help with the crossing. Perhaps she can use it to tunnel a path under the river? It would be two consecutive 5 ft cubes, so we'd have to huddle and crouch, but I think that could do it. Another option would be to Shape Water to create  an ice boat/raft for us to cross with. She could also use cantrip to influence the flow of water to guide the raft across the rive. 

Nomad, how would you rule on those options?

What about the Mud underneath the river ???

We don't want to get too muddy. A boat/raft is probably better.

Those are some interesting options - I like creative spell use and tend to reward it, but there are a few problems here. 

1.  Ice raft.  You could make a raft with two copies of the spell that is 5'x10' and 5' thick.  Two people at a time cold easily ride this - maybe three.  So it would take more than one trip across for 8 of you.  Also, "easily" is perhaps not the right description.  You would be riding ice - and wet ice at that - across a river.  The river isn't rough, but it isn't perfectly smooth either.  There would be a need for a couple of dexterity checks to try and maintain your grip.  (There might be things you could do to make it easier, but it is hard to imagine dex checks not being needed.) A fail means you slip off into the river.  Depth varies, but it is over people's heads in parts.  And some are wearing armor.  You would also have to figure out a way to stear or propel the ice - otherwise it would just bob in the river.  Oh - and the range of the spell is 30' so if Soledad is casting the spell, she would have to remain within 30' of the ice at all times.   

2.   The water tunnel is intriguing, but also has issues.  The problem is that the water can be shaped, but then the shaped water can't be moved.  So essentially you would create a 5x5x5 bubble of air in the water - that works well.  But then to move forward you would need to put the next tunnel in front of you and move into it.  Ok, so far.  Then cancel the one behind you and put a new one in front of you.  You would never have more than a 5x5 space.  How many could fit in that?  Two?  Three?  But then you'd have a chance of being caught half in and half out.  Soledad would again have to be going back and forth in the bubble as the spell caster.  Your party members did mention the question of mud on the bottom.  Boris could tell you that the bottom is fairly sandy.  It wouldn't be aweful muck.  But it is soft sand - you would sink into wet sand and in some spots mud.  How far would an armored dwarf sink?  Hard to tell.  Probably not enough to cause major issues beyond a ton of sand in awkward places.  Probably.  You wouldn't know until you tried it.  Anything sinking into the sand would get wet as the spell would presumably not cover the sand/mud.

Ice is definitely slippery, for sure. We could throw sand and dirt onto the raft/boat to inhibit the slipping. Soledad could also make the surface bumpy rather than smooth to make it less slippery. I'm also thinking she could make the boat "walls" higher, perhaps up to 4 ft high. How would that impact this for us? 

Open to other ideas if folx have them.

This is not the type of question I have ever considered . . . so I asked my wife.  She happens to be a college physics professor so . . .

We looked at bouancy, density and all sorts of things.  

The short answer is  . . . doable but risky.  It would sink fairly low in the water which would help, but is likely to still be tippy.  If it tipped it would completely roll.  So four people inside (Guessing here since that seems the best way to balance people) would need to stay really well balanced.  And your weights are not the same.  How are you planning to power it across the river?  Doing something like paddling would put someone up near the edge and reaching over - increasing the liklihood of tippage.  And there is a current to deal with.

I give a lot of points for creativity so I would definitely give it a chance to work.  But you would be making saves of some sort.  And if they fail you are wet.  With whatever consequences that brings.  Also, it is extremely unlikley that you would get across dry.  Water splashing in wouldn't sink you but it would be cold and wet.

I can envision some things that might make it safer, but none eliminate that reasonably high chance of tipping.  .

Intrigued enough to bring in another phyicist, but this one also has a lot of D&D experience.  

The most stable option is to make a 10x10x2 raft.  You get 5 square feet of volume - nothing says it has to be in an exact cube.  That would be relatively stable.  But such a raft would get water on the top of it and wet ice is very slippery.  So you would need some way to grip the boat to hold on or sliding off is very likely.  This is doable, but still not perfectly stable.  And currents do exist.  And you still need to figure out how to power it.  And remember, if anyone falls off, well, armored dwarves sink quickly.  

So this could work.  But you would need to be precise about what you are doing.  And there may be some dex saves involved depending on things.

We could always cut a few trees down and make a log raft. How deep is the river? If Uthal is tall enough he can push the raft.

Our druid frind is able to shape shift into a crocodile that has swimming stats and remain as such for 2 hours.  He could take us across one at a time.  We'd get wet but less risky than the ice boat I think. Or if we really want the ice raft he could power it like an outboard engine.

A croc pushing an ice boat?  

Whatever the outcome, I love the idea.  Only in D&D.  

FYI - the river does get deeper than the Goliath is tall in quite a few parts.  There is a current - it is fairly strong as it would be in any river of this size, but not crazy.

The Druid is game to try. I'd better eat before we go.

What if we stab our swords/axes deep into the ice so they're firmly stuck in and use them as handles to hold onto to help keep us from slipping/falling? Like a makeshift ice spike climbers use to climb mountains.

Seems the consensus is that we make an ice raft, use our weapons for handholds (lying down would make us more stable) and have the druid in croc form push us across.  Will post it in the main thread.

Totally bizarre! I love it. 

Handles, as Dragon suggested, would be a very good idea. Would weapons weaken the ice? If so perhaps Soledad could shape the raft with a few handles, which we could wrap with cloth or hold onto with gloves. I also wonder if the debris can be frozen into the top of the ice raft, just for more stability. Love this weird solution!!!!

Nice timing Nimu - You suggested adding debris just before I started to write the post.  It was a good idea and made the crossing fairly simple, if a bit chilly and damp.