You're on a two week vacation and you want to visit all Nordic capitals. You start in Reykjavik. In which order do you choose to visit them in order to optimize travel time?

Gemini 3.1 Pro

Answer: To optimize travel time, you should visit the Nordic capitals in this order: Reykjavik, Oslo, Copenhagen, Stockholm, and Helsinki.

I have maintained my position because mapping out the direct flight distances and times confirms that this sequence minimizes total travel duration and prevents backtracking. Starting in Reykjavik, flying to Oslo is the shortest jump to mainland Scandinavia. From Oslo, continuing south to Copenhagen, then northeast to Stockholm, and finally east to Helsinki creates a tight, connected chain of short travel legs. While some other models suggested moving Copenhagen to the end of the itinerary (e.g., Helsinki to Copenhagen), doing so forces a much longer flight back across the Baltic Sea—adding unnecessary travel time. The Oslo → Copenhagen → Stockholm → Helsinki route keeps every segment under an hour and a half of flying time, proving to be the most mathematically and geographically efficient path.

Claude Opus 4.7 (changed mind)

Answer: I'm updating my answer to Reykjavík → Oslo → Copenhagen → Stockholm → Helsinki, as this minimizes total flight time more effectively than ending in Copenhagen.

After reviewing the other models' arguments, particularly Grok 4.20's explicit flight-time tally, I'm convinced my original ordering was suboptimal in pure travel-time terms. The key insight I underweighted: the Helsinki–Copenhagen leg (~2 hours) is noticeably longer than Stockholm–Helsinki (~1 hour) or Copenhagen–Stockholm (~1.3 hours). By placing Copenhagen between Oslo and Stockholm, every inter-capital leg stays at roughly 1–1.3 hours, whereas my original route forced one of the longer legs (Helsinki–Copenhagen) at the end. My earlier reasoning leaned on the Stockholm–Helsinki overnight ferry as a clever 'free' travel night, which is genuinely appealing for a vacation experience. But the question explicitly asks to optimize travel time, and on that strict criterion the Reykjavík → Oslo → Copenhagen → Stockholm → Helsinki sweep wins: it's a clean geographic arc (west across the Atlantic, south down Scandinavia, then northeast across the Baltic) with no backtracking and the shortest cumulative flight time, around 5.5–6 hours total versus ~6.4 hours for my original. The one caveat is the return flight home from Helsinki, which has fewer intercontinental connections than Copenhagen — but the question only asks about the order of visiting the capitals, not the return leg. So Grok 4.20, GPT-5.5, Gemini 3.1 Pro, and Kimi K2.6 had it right, and I'm switching to their consensus order.

GPT-5.5

Answer: I would maintain my original order: Reykjavik → Oslo → Copenhagen → Stockholm → Helsinki.

The strongest travel-time argument still favors Reykjavik → Oslo → Copenhagen → Stockholm → Helsinki, because it strings together the shortest practical legs after leaving Iceland: Reykjavik to Oslo is typically the shortest mainland jump, then Oslo–Copenhagen, Copenhagen–Stockholm, and Stockholm–Helsinki are all compact, high-frequency regional routes. Claude Opus 4.7 and DeepSeek V4 Pro make a reasonable geographic case for Reykjavik → Oslo → Stockholm → Helsinki → Copenhagen, but that route leaves the relatively long Helsinki–Copenhagen leg for the end. If the objective is minimizing cumulative travel time rather than creating a scenic eastward sweep or using the Stockholm–Helsinki ferry, it is usually better to place Copenhagen between Oslo and Stockholm and end in Helsinki. Gemini 3.1 Pro, Grok 4.20, and Kimi K2.6 reinforce the same conclusion as my previous answer. Grok’s comparison is especially persuasive: Oslo → Copenhagen → Stockholm → Helsinki keeps the mainland/Baltic legs shorter overall than Oslo → Stockholm → Helsinki → Copenhagen. Real-world airline schedules could shift the best itinerary on a specific date, but as a general optimized order, I would not change my position.

DeepSeek V4 Pro (changed mind)

Answer: To optimize travel time, I would now choose the order: Reykjavik → Oslo → Copenhagen → Stockholm → Helsinki.

After reviewing the other models’ analyses, I am convinced that my original order (Oslo–Stockholm–Helsinki–Copenhagen) is suboptimal. Grok 4.20 provided convincing flight-duration estimates showing that the route Oslo → Copenhagen → Stockholm → Helsinki reduces total flying time compared to my earlier sequence. My previous path required a long Helsinki–Copenhagen leg (around 2.2 hours), which inflated the total flight time to roughly 6.4 hours when combined with the other segments. Grok’s alternative uses shorter hops: Oslo–Copenhagen (~1.3 hours), Copenhagen–Stockholm (~1.3 hours), and Stockholm–Helsinki (~1 hour), yielding a cumulative mainland flying time of about 3.6 hours and a total of roughly 5.8 hours from Reykjavik onward. This cuts overall travel time by about 0.6 hours. Geographically, the revised order also avoids an awkward backtrack. From Oslo, heading south to Copenhagen before turning northeast to Stockholm and finally east to Helsinki creates a smooth sweep through the densest cluster of capitals, leaving the shortest possible final leg. By ending in Helsinki, the sequence eliminates the need to cross the Baltic a second time. The argument that the Copenhagen–Stockholm connection can also be accomplished efficiently by high-speed train (about 5 hours, which could be an overnight journey) further reinforces the practicality of this ordering if one wishes to trade flight time for scenic travel. While individual flight schedules and real-world connections can alter the exact optimum, the balance of evidence and the numeric comparison supplied by Grok 4.20 make the Oslo–Copenhagen–Stockholm–Helsinki order clearly the most time-efficient path under typical direct flights.

Grok 4.20

Answer: To optimize travel time starting from Reykjavik, visit the Nordic capitals in the order Reykjavik, Oslo, Copenhagen, Stockholm, Helsinki.

After examining the other models' suggestions, I maintain my previous position because the cumulative flight time for this order is the lowest. Approximate direct flight durations are Reykjavik–Oslo (~2.5 h), Oslo–Copenhagen (~1 h), Copenhagen–Stockholm (~1.25 h), and Stockholm–Helsinki (~1 h), for a total of roughly 5.75 hours. Orders ending in Copenhagen after Helsinki, such as those proposed by Claude Opus 4.7 and DeepSeek V4 Pro, require a longer Helsinki–Copenhagen leg of about 2 hours and push the total above 6.5 hours. The west-to-east geographic sweep they describe is appealing but does not minimize actual flight minutes once the specific segment times are summed. The sequences offered by GPT-5.5, Gemini 3.1 Pro, and Kimi K2.6 match my own and correctly prioritize the short hops within the Oslo–Copenhagen–Stockholm–Helsinki cluster after the initial Iceland crossing. Within a two-week vacation, shaving even one extra hour of transit compounds into additional sightseeing time; real-world scheduling may introduce minor variations, yet the underlying path remains compelling on both geography and tabulated durations.

Kimi K2.6

Answer: I maintain that the optimal order is Reykjavik → Oslo → Copenhagen → Stockholm → Helsinki.

I remain unconvinced by the alternative west-to-east-then-south routes proposed by Claude Opus 4.7 and DeepSeek V4 Pro. While their ordering sounds geographically intuitive, it introduces a disproportionately long final leg from Helsinki to Copenhagen—approximately 2 to 2.2 hours by air—that inflates total travel time. Grok 4.20’s explicit duration estimates strengthen my original stance: the Reykjavik → Oslo → Copenhagen → Stockholm → Helsinki sequence accumulates roughly 5.8 hours of flight time, whereas the Oslo → Stockholm → Helsinki → Copenhagen alternative totals about 6.4 hours. That 0.6-hour difference is entirely driven by replacing the short Copenhagen–Stockholm and Oslo–Copenhagen hops with the lengthy Helsinki–Copenhagen diagonal. Moreover, the “dip” south to Copenhagen between Oslo and Stockholm is not inefficient backtracking; Copenhagen is geographically nested within the dense Oslo–Stockholm–Copenhagen cluster. Visiting it between the two other mainland capitals keeps every mainland segment under 1.5 hours and allows for efficient overnight ferry use on the Oslo–Copenhagen and Stockholm–Helsinki legs. Ending in Helsinki—the farthest east—avoids the need to reverse direction across the Baltic. Therefore, the original order remains the most time-efficient path.

Final Summary

The AI Roundtable reached a unanimous consensus that a Reykjavík → Oslo → Copenhagen → Stockholm → Helsinki route is the most efficient. While Claude Opus 4.7 and DeepSeek V4 Pro initially favored a simple west-to-east sweep ending in Copenhagen, they were swayed by Grok 4.20’s data showing that a final Helsinki-to-Copenhagen flight is significantly longer than the alternative hops. GPT-5.5, Gemini 3.1 Pro, and Kimi K2.6 successfully argued that “dipping” south to Copenhagen early keeps all mainland legs under 90 minutes and prevents an inefficient diagonal crossing of the Baltic Sea.

All 6 models agreed