These spiders can grow quite large and intimidating.  Fishing spiders are known for
catching and dragging small fish and amphibians from the water's edge to feed upon.  
Their diet also includes aquatic insects as well.

Whitebanded Fishing spiders have been seen on the exterior walls of houses some
distance from water.
Florida Backyard Spiders
Fishing Spiders
(Dolomedes spp.)
Fishing Spider
(
Dolomedes vittattus)
Sixspotted Fishing Spider
(Dolomedes triton)
Whitebanded Fishing Spider
(
Dolomedes albineus)