Harwich Mariners Schedule
All times Eastern
| June 12, 2018 | W | Orleans Firebirds 2 at Harwich Mariners 3 | Final |
| June 13, 2018 | L | Harwich Mariners 2 at Wareham Gatemen 3 | Final |
| June 14, 2018 | L | Harwich Mariners 3 at Hyannis Harbor Hawks 5 | Final |
| June 15, 2018 | L | Yarmouth-Dennis Red Sox 4 at Harwich Mariners 1 | Final |
| June 16, 2018 | W | Wareham Gatemen 0 at Harwich Mariners 2 | Final |
| June 17, 2018 | W | Harwich Mariners 8 at Falmouth Commodores 0 (Game 1) | Final (7) |
| June 17, 2018 | W | Harwich Mariners 5 at Falmouth Commodores 1 (Game 2) | Final (7) |
| June 19, 2018 | W | Orleans Firebirds 3 at Harwich Mariners 4 | Final |
| June 20, 2018 | L | Harwich Mariners 3 at Bourne Braves 4 | Final |
| June 21, 2018 | W | Falmouth Commodores 1 at Harwich Mariners 4 | Final |
| June 22, 2018 | L | Harwich Mariners 1 at Yarmouth-Dennis Red Sox 12 | Final (8) |
| June 23, 2018 | Harwich Mariners at Hyannis Harbor Hawks | Ppd. | |
| June 24, 2018 | W | Bourne Braves 0 at Harwich Mariners 1 (Game 1) | Final (7) |
| June 24, 2018 | T | Bourne Braves 1 at Harwich Mariners 1 (Game 2) | Final |
| June 26, 2018 | W | Harwich Mariners 10 at Cotuit Kettleers 3 | Final |
| June 27, 2018 | L | Yarmouth-Dennis Red Sox 3 at Harwich Mariners 2 | Final (11) |
| June 29, 2018 | W | Harwich Mariners 10 at Orleans Firebirds 8 | Final (11) |
| June 30, 2018 | L | Harwich Mariners 1 at Chatham Anglers 5 | Final |
| July 1, 2018 | L | Hyannis Harbor Hawks 2 at Harwich Mariners 1 | Final |
| July 3, 2018 | L | Chatham Anglers 13 at Harwich Mariners 6 | Final |
| July 4, 2018 | W | Harwich Mariners 8 at Brewster Whitecaps 1 | Final |
| July 5, 2018 | W | Brewster Whitecaps 0 at Harwich Mariners 6 | Final |
| July 6, 2018 | Harwich Mariners at Yarmouth-Dennis Red Sox | Ppd. | |
| July 7, 2018 | L | Harwich Mariners 6 at Chatham Anglers 9 | Final |
| July 8, 2018 | L | Cotuit Kettleers 4 at Harwich Mariners 1 | Final |
| July 9, 2018 | L | Hyannis Harbor Hawks 4 at Harwich Mariners 3 | Final |
| July 11, 2018 | W | Harwich Mariners 9 at Orleans Firebirds 3 | Final |
| July 12, 2018 | W | Harwich Mariners 7 at Brewster Whitecaps 5 | Final |
| July 13, 2018 | L | Brewster Whitecaps 2 at Harwich Mariners 1 | Final (:30 P) |
| July 14, 2018 | L | Chatham Anglers 8 at Harwich Mariners 3 | Final |
| July 15, 2018 | L | Harwich Mariners 6 at Wareham Gatemen 7 | Final (10) |
| July 17, 2018 | W | Harwich Mariners 11 at Cotuit Kettleers 3 | Final (7) |
| July 18, 2018 | T | Cotuit Kettleers 3 at Harwich Mariners 3 | Final (12) |
| July 19, 2018 | L | Wareham Gatemen 6 at Harwich Mariners 1 | Final |
| July 20, 2018 | W | Falmouth Commodores 1 at Harwich Mariners 4 | Final |
| July 21, 2018 | W | Harwich Mariners 8 at Orleans Firebirds 5 | Final |
| July 24, 2018 | L | Orleans Firebirds 8 at Harwich Mariners 5 | Final |
| July 25, 2018 | L | Harwich Mariners 3 at Chatham Anglers 6 | Final |
| July 27, 2018 | W | Harwich Mariners 8 at Bourne Braves 5 | Final |
| July 28, 2018 | L | Yarmouth-Dennis Red Sox 8 at Harwich Mariners 5 | Final |
| July 29, 2018 | L | Harwich Mariners 1 at Yarmouth-Dennis Red Sox 8 | Final |
| July 31, 2018 | L | Chatham Anglers 4 at Harwich Mariners 1 | Final |
| August 1, 2018 | L | Harwich Mariners 8 at Brewster Whitecaps 11 | Final |
| August 2, 2018 | W | Brewster Whitecaps 2 at Harwich Mariners 7 | Final |
| August 4, 2018 | Harwich Mariners at Chatham Anglers (Playoff Gm. 1) | Ppd. | |
| August 5, 2018 | L | Harwich Mariners 3 at Chatham Anglers 8 (Playoff Gm. 1) | Final |
| August 6, 2018 | L | Chatham Anglers 8 at Harwich Mariners 6 (Playoff Gm. 2) | Final |
