Deep blue against black is one of the most satisfying color pairings on a dive watch, and this 40mm Seastar 1000 Powermatic 80 shows why. The black PVD case and black rubber strap make a dark frame for a dial that shades from rich blue into near-black at its edges.

It is a mechanical watch at heart. Tissot’s Powermatic 80 winds automatically, keeps running for up to 80 hours off the wrist and relies on a Nivachron balance spring that is far less sensitive to magnetic fields than traditional hairsprings. A see-through caseback shows off the movement. The case is rated to 300 meters with a screw-down crown and back, and the bezel with mineral ring rotates anti-clockwise only, as a proper dive bezel should.

On its black FKM rubber strap the whole watch weighs just 93 grams, which makes it easy to forget you are wearing it. That lightness, plus the 40mm size, makes it a superb choice for swimming, travel and hot-weather wear.

Seastar 1000 Powermatic 80 40mm Blue Dial, Black PVD (T120.807.37.041.00)

• Case: black PVD-coated 316L steel, 40mm, 12.48mm
• Dial: dark blue gradient with luminous hands and indexes, date
• Bezel: anti-clockwise rotating, mineral ring
• Calibre: Powermatic 80 Swiss self-winding, Nivachron hairspring, 80-hour reserve
• Crystal: sapphire, anti-reflective underneath; see-through back
• Strap: black fluorocarbon rubber, standard buckle, 20mm lug width
• Weight: 93g
• Water resistance: 30 bar (300m)

Lightweight, mechanical and moody in all the right ways.