Eighth-tier Marine scored a 120th-minute winner to reach the FA Cup third round, while Hull - the highest-ranked team in round two - lost on penalties to League Two strugglers Stevenage.
There were nine second-round ties in all on Sunday, with Bristol Rovers thrashing non-league Darlington 6-0 and one side's players having to drive themselves to their game after a bus breakdown.
Fewer than half of the matches were decided in 90 minutes on a nail-biting day of cup antics. Below is our pick of the action.
- Watch all of the latest FA Cup highlights and reaction here
- FA Cup third round draw - which ball number is my club?
- Relive Sunday's FA Cup action
Merseyside minnows Marine get dramatic winner
Northern Premier League Division One North West side Marine are not classed as an elite club, meaning they had not played since their penalty shootout-win over Colchester in the first round because of coronavirus restrictions.
But they put any rustiness to one side as - with penalties looming - Niall Cummins scrambled in a free-kick with his back to defeat National League South club Havant & Waterlooville, who had Anthony Straker sent off just before the 90-minute mark.
"Inside I'm absolutely delighted. Every game my players surprise me even more," Marine manager Neil Young told BBC Radio Merseyside.
"I went running on the pitch, which is not my usual style - I'm usually quite calm."
It is the first time Marine have reached round three since the 1992-93 season and they will be one of two eighth-tier sides in the draw, with Canvey Island hosting Boreham Wood on Monday.
Stevenage stun League One leaders Hull
Stevenage came from behind to knock out 2014 finalists Hull on penalties, thanks to two spot-kick saves from on-loan Chelsea goalkeeper Jamie Cumming.
Tom Eaves' penalty looked to have put the Tigers on course for a regulation win but substitute Elliott List levelled to force extra time and then penalties - already Stevenage's fourth shootout of the season.
"It's the best feeling in football, you can't beat it really," Cumming told BBC Three Counties Radio.
"I was a bit annoyed I didn't save the one in normal time - I think I should've saved it.
"For it to go to extra time and penalties - it's what you dream of as a keeper - and I'm just glad I could come up with the goods again."
Rovers put six past Darlington
There was no such upset at the Memorial Stadium, where League One side Bristol Rovers scored all their goals in a 30-minute spell either side of half-time in their 6-0 thrashing of Darlington, who ply their trade three leagues below.
The sides are separated by 62 places but the Quakers started brightly until James Daly's goal, which opened the floodgates.
"Any win would have done for me but to score six goals and see the players play some really fluid and forward-thinking stuff made it that much more enjoyable," Rovers boss Paul Tisdale told BBC Radio Bristol.
Best of the rest
There was a shock of sorts at Plough Lane as League Two Crawley recovered to beat AFC Wimbledon, of League One, thanks to Ashley Nadesan and Max Watters.
Former Norwich and Birmingham striker Cameron Jerome struck late on to help League One side MK Dons avoid an upset against National League Barnet.
And it was an unfortunate day for National League side Dagenham & Redbridge, who took a first-half lead at League Two Mansfield but were eventually undone by a 122nd-minute Nicky Maynard winner.
That all came after the Daggers players had to drive themselves to Field Mill because the team coach broke down.