Undertow - A current below water surface flowing seaward; the receding water below the surface from waves breaking on a shelving beach.
Uni-knot – A popular basic knot or attaching line to hooks, swivels etc and can be used to join two lines together.
Uni-tech cast – A variation of the off the ground cast where the lead is laid out back towards the angler and inside the tip of the rod.
Uptider - a rod designed for uptide boat fishing with an extended handle below the reel seat to facilitate casting.
Uptiding - A type of boat fishing where the bait is cast uptide and away from the area around the anchor rope and boat. Grip leads are used and a belly is allowed to develop in the line after the rig settles. Bites from larger fish are normally slack liners. Originally developed in the shallow waters of the Thames estuary.
Upwelling - The movement of nutrient rich waters from the bottom of the ocean to the surface.
Velvet swimming crab – A small crab normally found below the low water mark. Has paddle shaped rear legs and a velvety texture to its carapace.
Venting - using a hollow needle to release excess gas from a fish caught in deep water to improve its prospects of survival. A legal requirement for reef fish in Florida.
VHF radio - VHF (Very high frequency) radios are those used in the marine environment for ship to ship and ship to shore communication. They generally have a line of sight transmission range.
Viviparous fish - Fish who give birth to live young. Unlike those of ovoviviparous fish, the developing embryos receive nourishment from the mother.