Upwelling – The movement of nutrient rich waters from the bottom of the ocean to the surface.
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.
Uptider – a rod designed for uptide boat fishing with an extended handle below the reel seat to facilitate casting.
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.
Uni-knot – A popular basic knot or attaching line to hooks, swivels etc and can be used to join two lines together.
Undertow – A current below water surface flowing seaward; the receding water below the surface from waves breaking on a shelving beach.