What is the furthest north and south you have been, not counting in an airplane?
Mine aren’t too extreme; Stockholm at about 59 deg. North and Buenos Aries at about 34 deg. South. I’d like to get north of the Circle one of these days and have a look around.
Drogheda, Ireland at 53.7 deg. North and Xel Ha, Mexico at 20 deg. N
Someday, when I’m rich and idle, I want to visit one of the poles in winter.
Montreal Canada at 45N and as far as I can think of south would be Nassau, Bahamas at 24N.
Anchorage is 61N and Durban, SA is 29S
I went north of the Arctic Circle (66.56N) once when visiting Sweden as a lad. It was July, and it was snowing! :eek:
I think the farthest north I’ve been is Bremen Germany. The farthest south I’ve been is definitely the Indonesian islands of Java and Bali, both a bit below the equator.
I’ve been to the Falklands, and I’ve flown over the North Pole… think I’m winning so far.
Edited to add: Just noticed aeroplane restriction. In that case Shetlands.
I can’t compete, but I like the idea of the thread, so I’ll contribute mine:
Bar Harbor, Maine to Sarasota, Florida. Puny by comparison.
North: Idaho/Canada border, 49° N.
South: Merida, Mexico and vicinity, approximately 20° N.
The edge of Harvard, at 42 north, and Tijuana, at 32 north.
I am planning to visit Seattle next month, though.
North: Helsinki (60 degrees north).
South: Either Julia Pfeiffer Burns State Park in California, or Virginia Beach, whichever is furthest south.
North: Fort William, Scotland, 56.82 degrees north
South: Cygnet, Tasmania, 43.09 degrees south
Dawson City, Yukon 64 degrees ish
La Paz, Bolivia 16 degrees ish
Ely, Minnesota 47 degrees 54 minutes north latitude
Plantation, Florida: 26 degrees 5 minutes north latitude
Someday I’ll have more impressive numbers, after I’ve visited Chile and Alaska.
North: Superior, Wisconsin 46.72N
South: Orlando, Florida 28.55N
I’m hoping to go a bit farther north and south, since that really isn’t that dramatic of a difference for my taste.
I suppose it’s the exact opposite of the question you’re asking, but I’ve stood exactly on the equator, with one foot in each hemisphere. I guess that’s extreme, in its own way. 
Northern most place I visited—Alaska
Southern most place I visited—Trinidad and Tobago
North: Alaska - just shy of the arctic circle ~ 66 deg. N
South: Fiji - only around 16 Deg. S
But on the longitude side I’ve been both to:
Greenwich: 0 deg.
and
Fiji (Taveuni): 180 deg.
65°N (North of Fairbanks, Alaska)
22°N (Cabo San Lucas, Mexico)
North: Yellowknife, NWT, Canada: 62 degrees N
South: Perth, WA, Australia: 31 degrees S