This table shows all the countries in Europe (and surrounding area)
It is sorted by default in the order of the number of ferns in each country but it can be sorted in any order you like by clciking on the title of the column you are interested in
The data for the fern count comes from Hassler, Michael (2004 – 2020): World Plants. Synonymic Checklist and Distribution of the World Flora. Version 11.1; www.worldplants.de

Saba is number 1 in the ferniest places in the World

Saba, a Caribbean island in the Lesser Antilles chain, is a special municipality of the Netherlands. Measuring just 13 square kilometers, it consists essentially of the top of the dormant Mount Scenery volcano (887 m).
Additions to the Fern Flora of Saba, Netherlands Antilles, DAVID B. LELLINGER, American Fern Journal 92(2):93-96 (2002)
There is tourist information here
There is information on accomodation here

American Samoa is at No 15 in the ferniest places in the World
It also has a large number of ferns (152)
There is more information about the botany of these islands here, including 2 useful reports by Dr. W. Arthur Whistler:
Technical Report 83: botanical inventory of the proposed Ta’u unit of the national park of American Samoa; February 1992
Technical report 87: botanical inventory of the proposed Tutuila and Ofu units of the national park of American Samoa; April 1994
The following maps are taken from Technical Report 83

This table was extracted from the website

This is a table based on the work of Hassler, Michael (2004 – 2020): World Plants. Synonymic Checklist and Distribution of the World Flora. Version 11.1; last update Dec. 8, 2020. – www.worldplants.de
The regions and the fern count (including endemics) come from his website. The area information (km²) comes from a variety of sources
The table is sorted by default by the largest value for ferns/km² but you can resort the table by clicking on any column header

I have a Sony α6100 camera which I can control from my PC using Sony’s remote viewer software
With this software I can “tether” the camera and adjust the focus very accurately
This is my “rig”

It comprises a
single monitor stand
Pro 4 Way Macro Focusing Focus Rail Slider for Close-up Shooting with a DSLR Camera
Ring flash light
(I have added links to similar but not necessarily the same items as I bought)
(The ring light was designed to work on batteries but I found I could hard wire it to the mains via a USB power supply)
With this set up I can control the exact position of the camera in a stable situation

I take a series of pictures, changing the focus very slightly for each picture
This change of focus is done using Sony’s software on the PC and I do not have to touch the camera itself
Here is an example of the series:

I then combine these images using Picolay
This software can combine all theses images and produces this image, which is a combination of all the in-focus bits of the previous 22 images:

This image when looked at full pixel size will produce a picture like this:

and then if I sharpen the image using the Nik Collection plugin for Photoshop elements

The end result of this is not to get a greater magnification than the camera lense can achieve but to get a greater depth of focus than the camera can achieve on its own

Singapore is a small island (280 square miles)
For the British, it is about half as big again as the Isle of Wight

It is a popular holiday and stop-over destination
Here is a map showing the fern locations of Singapore taken from the data published in The urban pteridophyte flora of Singapore by Benito C. Tan, Angie Ng, Angie Ng-Chua L.S., Anne Chong, Cheryl Lao, Cheryl Lao,Machida Tan-Takako, Ngiam Shih-Tung, Aries Tay & Yap Von Bing

The locations are shown (by default) grouped by the numbers of ferns in each location
The highest number of ferns is in the Central Catchment with 16
You can also see the ferns in each of the locations described in the paper by chosing “Fern locations” in the legend
Clicking on any location will bring up the list of ferns in that location