D&D 5E How to get an undead army across an ocean?

[Lidgar]

They cross in a Necroberg powered by zombie seals. This only works if you're not in the tropics; there they cross in a Big Gulp Necroslushie.

 

[rgoodbb]

Gliding-ships pulled by enlarged Crawling Claws along the ocean bed.

Also, depends on whether Zombies/Skeletons float or sink...

 

[Imaculata]

"Gents... take a walk!"

 

[Satyrn]

"Grab one and start swimming"

 

[LordEntrails]

Use repeated castings of wall of stone to build a bridge across the sea.

Supposing you want the six-inch-thick version, and half-length because the span is greater than 20 feet, and the lich is willing to burn 5 spell slots per day on this, you'd get 250 feet of bridge per day. Suppose they made the bridge at a narrow point that was only 250 miles across, you'd need 5,280 days of casting -- a little under 14 1/2 years! That's, like, no time at all for a lich.

No one will see that coming!

 

[Satyrn]

Use repeated castings of wall of stone to build a bridge across the sea.

Supposing you want the six-inch-thick version, and half-length because the span is greater than 20 feet, and the lich is willing to burn 5 spell slots per day on this, you'd get 250 feet of bridge per day. Suppose they made the bridge at a narrow point that was only 250 miles across, you'd need 5,280 days of casting -- a little under 14 1/2 years! That's, like, no time at all for a lich.

Even better, build this stone bridge underwater, where the continental shelf drops off into the abyss.

And maybe some other lich altrady did this some time ago in the past, and this lich is just exploiting its existence.

 

[JeffB]

A causeway made of bodies and bones.

 

[Guest 6801328]

In how much time? I’m picturing one at a time using a really, really big trebuchet.

 

[SkidAce]

Use boats?

 

[77IM]

Since they don't need to breathe, you could stuff them all into portable holes. Or craft a really big one (portable cavern?).