These are the best Zeiss lenses for underwater photography when you want edge-to-edge clarity behind a dome, strong contrast, neutral color, and precise focusing for reefs, wrecks, CFWA (close-focus wide-angle), ambient-light scenics, macro critters, and product-like pool work—and here’s what to look for as you buy: choose rectilinear wides that behave well behind domes (clean corners at ƒ8–ƒ11, minimal field curvature), true macros with generous working distance for strobes/snoots, declick/long-throw MF when you pull focus through a mask, and housings/ports that match each lens (large domes for blue-water scenics, mini-domes for CFWA, flat ports for macro); skip CPLs underwater (they cost light and blotch), favor compact barrels that take focus gears easily, and standardize step-ups for one protective UV when topside. Full-frame wide heroes for domes: Batis 18mm ƒ2.8 (AF, featherweight, disciplined corners—great reef/wreck scenic), Batis 25mm ƒ2 (blue-hour pools/caves and mixed-light work), Loxia 21mm ƒ2.8 and Loxia 25mm ƒ2.4 (manual focus with long, silky throws and declick—cine-friendly UW video, gorgeous sunstars topside), plus DSLR/adapted classics Milvus 18mm ƒ2.8 and Milvus 21mm ƒ2.8 for robust mechanics and T* coatings; if you want the dramatic bend of a fisheye for CFWA, adapt the F-Distagon 16mm ƒ2.8 (diagonal fisheye) and choose an appropriate dome—get inches from the subject for scale. Macro kings behind flat ports: Milvus 100mm ƒ2 Makro-Planar (1:2, beautiful micro-contrast and working distance for shy subjects), Milvus 50mm ƒ2 Macro (1:2 for fish portraits and product-style pool shoots), and Sony E-mount Loxia 65mm ƒ2.4 Macro (1:2, compact, precise MF for video pulls); APS-C shooters get true 1:1 with Touit 50mm ƒ2.8 Macro and a tight, lightweight rig. Hybrid zoom/coverage note: for travel rigs the Vario-Tessar FE 16–35mm ƒ4 ZA OSS pairs well with large domes for honest corners and flexible framing (confirm gear/port charts for your housing), while the Vario-Tessar E 16–70mm ƒ4 ZA OSS on APS-C does practical fish/portrait work—use a diopter behind flat ports if your housing system calls for it. Practical buyer tips: build a two-lens spine (one dome wide + one macro)—e.g., Batis 18/2.8 (large dome) + Milvus 100/2 (flat port), or Loxia 21/2.8 (mini-dome CFWA) + Loxia 65/2.4 (flat port)—and add the 16/2.8 fisheye for dramatic CFWA sets; verify port extensions, focus/zoom gears, and minimum focus behind dome for each lens before a trip; carry a strong focus light, spare o-rings, and silica packs, and keep front elements immaculate. Underwater shooting tips: get close (water steals contrast)—within 1–3 ft; for strobes, toe them out to reduce backscatter and angle slightly forward for edge glow, keep shutters near sync (≈1/160–1/250 s), run ƒ8–ƒ13 for wide-angle corner discipline and ƒ16–ƒ22 for macro depth, and let ISO float conservatively; for ambient-light scenics, shoot upward with Batis/Loxia wides, expose for blue water, and add a modest stop-down to tighten corners; for macro, use a flat port, low-power short-duration strobe pops, and move the rig (not the focus) for micro-adjustments—focus peaking helps through a mask; for video, lock a 180° shutter with a good VND topside but go bare underwater, prioritize stable buoyancy/trim over IBIS, and keep moves slow—micro-wobbles read large; whether you’re building dramatic CFWA reef portraits, clean wreck panoramas, black-background critter shots, or pool fashion/product, the best Zeiss underwater choices—Batis/Loxia/Milvus wides for domes, Milvus/Touit/Loxia macros for flat ports, and the adapted 16/2.8 for fisheye drama—combine disciplined optics, trustworthy coatings, and precise focus so your water stays blue, your corners stay crisp, and your subjects pop with minimal backscatter.