Exciting Historical information you need to know about shipping Manure:
In the 16th and 17th centuries, everything had to be transported by
ship.. It was also before commercial fertilizer's invention, so large
shipments of manure were common. It was shipped dry, because in dry form
it weighed a lot less than when wet, but once water (at sea) hit it, it
not only became heavier, but the process of fermentation began again, of
which a by-product is methane gas.

As the stuff was stored below decks in bundles you can see what could
(and did) happen. Methane began to build up below decks and the first
time someone came below at night with a lantern, BOOOOM! Several ships
were destroyed in this manner before it was determined just what was
happening.

After that, the bundles of manure were always stamped with the term
"Ship High In Transit" on them which meant for the sailors to stow it
high enough off the lower decks so that any water that came into the
hold would not touch this volatile cargo and start the production of
methane.

Thus evolved the term "S.H.I.T," which has come down through the
centuries and is in use to this very day.