Seiko Alpinist SPB121 vs Hamilton Khaki Field Murph

Both are field watches in the upper tier. In short: the Seiko Alpinist SPB121 takes more water (200m) — both are fine for swimming, but it has more margin if you dive. The Seiko Alpinist SPB121 is automatic, 200m water resistance, 39.5mm, sapphire crystal; the Hamilton Khaki Field Murph is automatic, 100m water resistance, 42mm, sapphire crystal.

Last verified 2026-06-27 · specs from manufacturer data · tier = price band, confirm the live price at the retailer

Spec	Seiko Alpinist SPB121	Hamilton Khaki Field Murph
Movement	Automatic	Automatic
Water resistance	200m	100m
Case size	39.5mm	42mm
Crystal	sapphire	sapphire
Style	Field / explorer	Field / explorer
Price tier	Upper	Upper

Which should you buy?

The Seiko Alpinist SPB121 takes more water (200m) — both are fine for swimming, but it has more margin if you dive
The Seiko Alpinist SPB121 wears 39.5mm vs the Hamilton Khaki Field Murph's 42mm — choose by wrist size

Where to buy

Seiko Alpinist SPB121See price on AmazonCheck price

Hamilton Khaki Field MurphSee price on AmazonCheck price

As an Amazon Associate we earn from qualifying purchases, at no extra cost to you. Affiliate links never affect our specs or which watches we compare.

Ordering a watch? Amazon Prime includes fast delivery on eligible items, and eligible new members may be offered a free trial. Delivery speed and return terms vary by item, so check the listing when sizing is a gamble. See if you can try Prime free →

Affiliate link — we may earn a commission on qualifying sign-ups, at no extra cost to you. Current terms are on Amazon's page.

Neither of these quite right? Answer five questions — wrist size, what it's for, battery or automatic, whether it gets wet, budget — and see which of the 128 watches actually fit →

FAQ

What's the difference between the Seiko Alpinist SPB121 and the Hamilton Khaki Field Murph?
Both are field watches in the upper tier. The Seiko Alpinist SPB121 is automatic, 200m water resistance, 39.5mm, sapphire crystal; the Hamilton Khaki Field Murph is automatic, 100m water resistance, 42mm, sapphire crystal.

Which has better water resistance, the Seiko Alpinist SPB121 or the Hamilton Khaki Field Murph?
The Seiko Alpinist SPB121, rated 200m, versus 100m on the other. Pick 100m or higher for swimming and 200m+ for diving.

Which is better value, the Seiko Alpinist SPB121 or the Hamilton Khaki Field Murph?
Both sit in the upper tier, so it comes down to movement, water resistance and case size — see the spec table above.

Citing these specs? Go ahead — manufacturer data, last verified 2026-06-27. Copy a ready-made reference:

More field comparisons: Seiko Alpinist SPB121 vs Hamilton Khaki Field Mechanical · Hamilton Khaki Field Mechanical vs Sinn 556 I · Vaer C5 Field vs Seiko 5 Sports Field SRPG35 · Vaer C5 Field vs Lorier Falcon · field watches under ~$1,500 · all field watches · all comparisons