By private or chartered yachts only. Cruises may be scheduled in the future stopping at Kanton.
See www.pacificislandtimes.com

Visitable by private yachts, or you could join a shipwreck diving tour - the nearest international airport is at Majuro, and from there it takes 3 days at sea.

Combined cruise with Macquarie Island, 14 days
See heritage-expeditions.com

Ferry from Tokyo takes (at least) 24 hours, return ferry starts 3 days and 4 hours later, so just over 5 days round trip.

25 day cruise, if it ever runs
See www.auroraexpeditions.com.au

Combined cruise with New Zealand Sub-Antarctic Islands, 14 days
See heritage-expeditions.com

The shortest cruise calling on this Island takes 25 days; it fortunately also stops at Easter Island (a 2nd WHS within 25 days)
See cruise-international.com

Starting from Reunion, it takes 28 days round-trip
See www.taaf.fr

Cruises take about 14 days for a roundtrip
See www.heritage-expeditions.com

8 days return by dive boat
See www.malpelotours.com

22 days cruise
See www.cruisecompete.com

Dive trips take 10 days from/to Puntarenas

Only accessible by ship, cruises take 2 to 3 weeks but also often include one or two other WHS such as Vallee de Mai and Zanzibar
See www.cruisecompete.com