Learn Icelandic: Það er rekaviður alls staðar eftir óveðrið. - There is driftwood everywhere after the storm.

It is composed of the genitive (possessive) forms of allur (all) and staður (place), literally meaning "of all places." This is a fixed phrase used as a static adverb. Because the driftwood is simply resting there rather than moving toward a destination, this static location word is the correct choice.

Why is the verb singular (er) if the driftwood is everywhere?

Just like "driftwood" in English, rekaviður is an uncountable mass noun. It acts as the true subject of the sentence despite being pushed back by the dummy subject það (there). Because mass nouns can't be counted, they take the singular verb er.

How does the prefix in óveðrið change its meaning?

The noun óveðrið combines the negative prefix ó- with veður (weather). In Icelandic, adding ó- to weather specifically means "bad weather" or "storm." The -ið at the end is the neuter definite article ("the").

Why is óveðrið in the accusative case here?

The preposition eftir governs the accusative case when it means "after" in a timeframe. If it meant "along" or "according to," it would take the dative case. Because óveðrið is a neuter noun, its accusative form happens to be identical to its nominative form.