The best robotic pool cleaner for an inground pool

Who this is for

Read on if your pool is permanently in the ground, close to the length this page assumes, and you want the walls cleaned rather than just the floor. Everything judged here is a self-contained robot that plugs in or charges up, not a pressure-side or suction-side cleaner that hangs off your filter system. If your pool is an above-ground one that comes down for the winter, read The best robotic pool cleaner for an above-ground pool instead: the makers rate those separately, and of the picks here only the Aiper Scuba S1 is marketed for that job at all. And if you have already narrowed it to the Dolphin, the Aiper and the Wybot, Dolphin Nautilus CC Plus vs. Aiper Scuba S1 vs. Wybot sets those three side by side.

Your house, in the makers’ own terms

Makers describe a pool cleaner in three published facts and this page checks each. Pool type comes first: the maker either sells the machine for a pool set in the ground or it does not. Pool length is the maker's statement of the longest pool the machine is meant to keep on top of, not an area. Wall climbing is a yes or a no, and on some models a separate line says whether it also scrubs the waterline, the tile band at the surface. This pool is 35 feet, inground, walls included.

Against those three the field thins without emptying. The Dolphin Nautilus CC Plus is rated to 40 ft and both other picks to 50 ft, so all three clear this pool, the main pick with the least margin. Of everything judged, 3 units are out on one of those three, most because their makers sell them for above-ground pools. A further 5 could not be judged at all, and not for one shared reason: on some the maker never states a pool length, on others never says whether the machine climbs walls or which pools it is for. The published limits hand you a shortlist and stop there. What separates it is the waterline, the cord, and what happened when testers put each machine in a pool.

An inground pool 35 feet long, walls included, run against all 13 robotic pool cleaners we track: 5 clear every published limit this house turns on, 0 clear them at a limit, 3 miss one, and 5 could not be judged because the maker does not publish the limit. Every figure is from the maker’s own page or manual; nothing here was tested by us. The method.

The first month

The water has to be right before the machine goes in. Maytronics' manual sets a pH window and a ceiling on salt content that the pool must be inside before the cleaner runs, and the set-up line in the fact list under the pick carries both figures, so test a salt pool against them before the first cycle rather than after it. All three picks then want the same small habit, which is the filter seen to when the cycle ends rather than at the weekend.

The first cycles are where you learn what your pool does to a robot. Watch where each one ends and what it leaves behind, because the places testers got stuck on these machines are the deep end, tight corners and the steps, and those are the spots you will be finishing by hand if they turn out to be yours.

Setting it up

Maytronics' instruction is not to plug the power supply in until the cleaner is already in the water, and to run it only from a ground-fault-protected outlet. Take the robot out before anyone swims, and cut the power before you work on it. Maytronics says the Dolphin Nautilus CC Supreme needs no booster pump and no extra plumbing, and publishes no such line for the Dolphin Nautilus CC Plus.

When the cycle is done, coil the cable and store the unit somewhere dry, cool and out of direct sun. The Scuba S1 has no cord to place, but Aiper says it should not be left sitting in pool water for more than a fortnight, even in its low-power mode.

Buying it right

Maytronics lists the Dolphin Nautilus CC Plus at $849 and shows a lower sale price on the same page, so treat list as a ceiling. Aiper prints no price on its marketing page; the $500 list figure beside the Amazon price comes from Aiper's own storefront. Two Amazon listings rate the Dolphin Nautilus CC Plus for a longer pool than Maytronics' own 40 ft, and the maker's figure is the one judged here. A Dolphin warranty holds only if the robot came from an authorized Maytronics dealer, and a listing will not tell you whether the seller is one.

Dolphin Nautilus CC Plus

• The listing we verified: “Dolphin Nautilus CC Plus Wi-Fi Automatic Robotic Pool Vacuum Cleaner, Always Cleaning, Never Charging, with Wall Climbing Scrubber Brush, Ideal for In-Ground Pools up to 40 FT in Length”, $749 when checked. Brand and full model name in the listing's own title; the listing's SKU 99996406-PCI differs from the maker's 99996409-PCI (an edition of the same model, by the maker's own numbering).
• “Dolphin Nautilus CC Automatic Robotic Pool Vacuum Cleaner, Wall Climbing Scrubber Brush, Top Load Filter Access, Ideal for Above/In-Ground Pools up to 33 FT in Length”, $699: a different model that a search for this one returns.
• “Dolphin Nautilus CC Plus Wi-Fi Automatic Robotic Pool Vacuum Cleaner, Includes Caddy and Classic Cover for Storage and Protection, Ideal for In-Ground Pools up to 50 FT”, $968: An accessory or part listing ('cover for'), not the unit.
• “Dolphin Nautilus CC Plus Wi-Fi Robotic Pool Vacuum Cleaner Includes Ultra-Fine Filters for an Ultimate Clean, Ideal for In-Ground Pools up to 50 FT in Length”, $899: An accessory or part listing ('filters for'), not the unit.

Aiper Scuba S1

• The listing we verified: “Aiper Scuba S1（2024） - Robotic Pool Cleaner, Powerful Suction, 150-Min Runtime, Wall & Waterline Cleaning, for Inground & Above Ground Pools up to 1600 sq.ft”, $450 when checked. Brand and full model name in the listing's own title; no bundle, variant or accessory marker.
• “(2026 Upgrade) (Renewed) Aiper Scuba S1 Robotic Pool Cleaner,270 Min Runtime, Floor/Wall/Waterline/Shallow Area Cleaning, Ultra-fine Filter, Smarter Navigation, App Support-Black”, $400: Refurbished or used listing.
• “Aiper Scuba S3 Robotic Pool Cleaner for All Inground Pools, Obsidian”, $650: a different model that a search for this one returns.

Dolphin Nautilus CC Supreme

• The listing we verified: “Dolphin Nautilus CC Supreme Wi-Fi Automatic Robotic Pool Vacuum Cleaner, Dual Drive, Waterline Scrubber Brush, Top Load Filter, Ideal for In-Ground Pools up to 50 FT”, $1,449 when checked. Brand and full model name in the listing's own title; no bundle, variant or accessory marker.
• “Dolphin Nautilus CC Supreme Wi-Fi Automatic Robotic Pool Vacuum Cleaner Includes Caddy and Classic Cover for Storage and Protection, Ideal for In-Ground Pools up to 50 FT”, $1,568: An accessory or part listing ('cover for'), not the unit.
• “Dolphin Automatic Robotic Pool Vacuum Cleaner, Wall Climbing Scrubber Brush, Smart Navigation, Ideal for In-Ground Pools up to 40FT in Length - Nautilus CC Plus”, $829: a different model that a search for this one returns.
• “Dolphin Nautilus CC Supreme Wi-Fi Automatic Robotic Pool Vacuum Cleaner Includes Caddy, Easy to Transport and Store, Ideal for In-Ground Pools up to 50 FT in Length”, $1,548: a bundle, not the bare unit; the extra hardware is in the price.

What this page can’t promise

Nothing on this page was tested by us. The measurements and verdicts come from named testers, and the build links each one under the pick it belongs to, so you can read the source yourself. That matters more here than on most pages, because the testers disagree sharply about the main pick and line up against the cordless one.

The makers do not always agree with themselves either. Aiper's page calls the Scuba S1 a cleaner for both above-ground and inground pools in its marketing copy, while the spec table underneath it lists inground only. Where a maker contradicts itself like that, this page says so rather than take the better number and move on.

This page reads a maker's pool-length rating, which is written for a plain rectangle, so it cannot see your corner steps, your tanning ledge, your main drains or your leaf load, and it cannot know how a battery that testers found short of its claim will do in a pool the size of yours.

The competition

Every pool robot we track was judged against the same house. The verdict column names the maker limit that decided it.

Other houses we judged

• Half acre, no wireThe best robot lawn mower for a half acre with no perimeter wire

  A half-acre lawn, one continuous piece, a slope you notice when you push a mower up it, and no wire you are willing to bury. Every robot mower we track, judged against that yard from the limits its own maker publishes.

• Small yardThe best robot lawn mower for a small yard

  A small suburban lawn, a gentle grade, and a couple of beds to steer around. Almost every robot mower we track clears a yard this size, so the question stops being which one is big enough and starts being which one is worth what it costs.

• Above-ground poolThe best robotic pool cleaner for an above-ground pool

  An above-ground pool 24 feet across, on a soft liner, with a wall you can reach over. The maker's own pool-type rating decides this page before anything else gets a say: it rules out 4 of the 13 cleaners judged here on its own.

• ComparedDolphin Nautilus CC Plus vs. Aiper Scuba S1 vs. Wybot

  Dolphin Nautilus CC Plus, Nautilus CC, Aiper Scuba S1 and two Wybots on the makers' own figures, then judged against one inground pool with walls.

• Three catsThe best automatic litter box for multiple cats

  3 cats, one of them big and one of them small, and one box that has to serve all of them. Two published limits decide it: the number of cats the maker rates the box for, and the weight range its sensors were built around.

• Pet hair, hard floorsThe best robot vacuum for pet hair on hard floors

  A shedding dog or two cats, hard floors through most of the house, low thresholds between the rooms, and a wish that the bin emptied itself. Every robot vacuum we track, judged against that house from the limits its maker publishes rather than from a lab's dust-pickup score.

• GuideMeasure before you buy

  Every home robot is sold against a limit, and every maker calls that limit something different on its spec page. Here is how to get your own numbers first.

• GuideApps, subscriptions and what stops working offline

  Every one of these machines still moves without the internet. What you lose is the map, the schedule, the history and, on some of them, the reason you paid extra.

• GuideRecalls and battery safety for home robots

  Five recalls cover every robotic pool cleaner, mower, vacuum and litter box sold in the United States since 2020, and every one of them was about heat.