You should not end a sentence with a prepositionAerroMatt said:... "Piers" are what you go fishing from, or tie your boat or ship to.
Just my $.02
"Piers are structures from which you fish or to which you tie your boat or ship" is correct.
"Piers" are what you go fishing from, or tie your boat or ship to, you chowderhead" is also acceptable.