
40 watches that match on case size, movement family, and price band. Sorted by how close the match is.
The closest alternative to the Seiko Monster is the Seiko Prospex Sea Save the Ocean Special Edition ($550) — shared caliber (Seiko 4R36) and Same family (Prospex Sea). If price is the constraint, the Swatch Sistem Sea at $170 (vs $550 for the Monster) covers most of the same brief. From the independents, the Borealis Watch Co. Estoril 300 GMT is the standout microbrand take — common cross-shop and Pro diver. Stepping up, the Seiko Prospex Sea Seiko Diver’s Watch 60th Anniversary Limited Edition ($1,750) is where the same idea goes with a bigger budget.
Independent makers covering the same brief — usually with something the mainstream brands don't.
Established brands covering the same brief at a comparable price — same case size, similar movement family. Often the deciding click for a new buyer.
If the price is the only thing keeping you off this watch, these get you most of the way there for less.
Where the same idea goes when budget isn't the constraint — luxury upgrades and step-ups.