So long, and thanks for all the ghoti. -- Anon Guest
They were large, piscine lifeforms, big enough to swallow a Goliath whole, and the lake they inhabited was as large as an entire country. It would take too long to go around. They had to go across somehow.
"You can fly, right?" said Anthe. "Just zip us across?"
Wraithvine said, "Look for what isn't here," and summoned an illusory globe via Prestidigitation and floated it out over the surface. It fizzled and died when the water was just deep enough to drown in. "Anti-magic field."