What are your geographic extremes

[Crumpets]

North: Keflavik Airport, Iceland (63°59'44" N) (2011)
South: Just Northeast of downtown Singapore (1°19'11" N) (2011)

By latitude/longitude:
East: Narita Airport, Japan (140°23'21" E) (2011)
West: Just West of Kauai (159°48'25" W) (2008)

By heading:
East: Binsar, India (79°45'46" E) (2010)
West: Lat Krabang, Thailand (100°44'24" E) (2011)

[Crumpets]

Furthest North: Vancouver, Canada (2015) 
Funny I didn't even think about it at the time, but looking at a map it's definitely true.

Furthest South: Cabo Rojo, Puerto Rico (2014)
Also didn't realize this was the case.  Puerto Rico is indeed a couple degrees south of Hawaii.

Furthest West: Waimea Canyon, Kauai, Hawaii (2009)

Furthest East: Ceiba, Puerto Rico (2014)

Don't you live in Bellingham? And the farthest north you've been is Vancouver? You should just get up early some morning and drive up to Whistler or something just to bump it.

[Crumpets]

how do you guys travel so much? literally the furthest west I've been is 40 miles from the house I lived in as a teenager lol

Almost all of my geographic extremes are from volunteer trips. They're a great way to travel somewhere cheaply, get to know the place on a better level than just being a tourist, and feel like you're actually giving something back to the place where you're travelling.

[Crumpets]

By lat/long:
North: Keflavik Airport, Iceland
South: Singapore
East: Narita Airport, Japan
West: Off the western shore of Kauai, HI


By heading:
North: Keflavik Airport, Iceland
South: Singapore
East: Binsar, Uttarakhand, India
West: Lat Krabang, Thailand

[Crumpets]

By lat/long:
North: Keflavik Airport, Iceland
South: Singapore
East: Narita Airport, Japan
West: Off the western shore of Kauai, HI


By heading:
North: Keflavik Airport, Iceland
South: Singapore
East: Binsar, Uttarakhand, India
West: Lat Krabang, Thailand

If layovers don't count, then Denali National Park instead of Keflavik for North and Hanoi instead of Narita for East by longitude.

[Crumpets]

(The furthest place you have visited in each of the four cardinal directions)

Northernmost: Mammoth Hot Springs, Yellowstone National Park, Wyoming.
Southernmost: Tombstone, Arizona.
Easternmost: Washington D.C.
Westernmost: Muir Woods National Monument, California.

Updated, amusingly these have all been on trips with atlas posters-

Northernmost: Seattle, WA (with rfayette, crumpets, and mechaman)
Southernmost: Galveston, TX (with rfayette)
Easternmost: Portland, ME (with mattvt, sawx, and zen lunatic)
Westernmost: Eureka, CA (with sprouts)

I had no idea Seattle was your northern extreme or I would have taken everyone to Green Lake or Carkeek Park just to pad your numbers a little more!