Furthest south was Porto Allegra Brazil (yuk ).
Wait......you pay money to travel?Lucky! You must do all your travel now using accumulated frequent traveler miles. Are you on the Greyhound or the Trailways program?
Wait......you pay money to travel?
North Slope of Alaska to Aruba.
East-West: Started out traveling west from Houston to Yuzhno-Sakhalinsk (Far East of Russia) via Tokyo. Continued westward to Moscow. Westward again back to Houston.
I doubt whether anyone who hasn't visited the Dead Sea area can do better than tie my record for lowest point visited.
In 2004 I was visiting Death Valley in California, and I went to the lowest point on the surface of North America at Badwater Basin. They had a little parking area and it's marked as 282 feet (86 meters) below sea level.
Of course I wasn't satisfied with the visitor spot so I took my handheld Garmin and went on a hike across the salt flats until I was sure I was at the absolute lowest point. Then I scooped up about a tablespoon of the salt/sand mixture and took it home in a plastic bag to add to my collection. I have small pebbles from many of the extreme points I've visited.
I'm sure there are some here who have been deeper in the ocean, but the dry land low points are few and far between.
Edited to add that I didn't think about down in mineshafts, only surface points.
Yes, I went to the Dead Sea (1388 ft below sea level) in 2009.
Since people are quoting north too, mine is Cantwell, AK (not counting Iceland, since I never left the airport, I can't say I've really "been there").
Google Maps allows a cool thing: how far apart is your southernmost destination from your northernmost? 9,847 miles for me, but it's not got too much of an east-west angle to it, so others will have longer distances.
Cozumel and likely near the Aleutions on a flight from Seattle to Tokyo.
Dang, Yuzhno-Sakhalinsk is WAAAAY out there! How many days was your drive to Moscow from there? DH took about a week or so to drive from Ulan Ude to Vladivostok, on the "good" highway. I guess you did some time on the Road of Bones to be that far out.
Very cool.