*EDITORIAL* Understanding Ham Islomaniacs

While ham radio ‘islomaniacs’ such as island hunters, DXpeditioners and the like confess a fascination for all islands, some find ‘absolute irresistibility’ with 1 or more types.  This can be evidenced through a dx adventurer’s choice of island DX-stinations, by his success in island award programs (e.g. I.O.T.A.), by his amount of financial sponsorship for different island DXpedition teams, as well as numerous other hobby indicators too.

To be able to articulate a ham islomaniac’s preferences more eloquently, let’s take a look at the different sorts which make up the world’s 200 000 odd islands; as well as some of the terminology commonly used by islomanes inhabiting the ham radio community to classify them…

It’s generally accepted by geographers that there are 2 types of islands, all depending on how and where they’re formed.  Within these 2 types also exist a number of fascinating sub-types!


Generally easier to access for aspiring dx adventurers and therefore more often QRV on the bands, these are bodies of land connected to a continent that tend to sit in shallow waters of 200 m or less.

Continental islands are most often formed when sea levels rise, causing low lying areas to fill up with water, splitting off parts of the land higher above sea level.  An example of this is Manhattan (NY011R), a famous US island situated at the mouth of the Hudson River in New York now connected to the mainland by bridges.

Continental islands are also created when water cuts through a peninsula effectively isolating it from the mainland.  The Southeast Asia country of Malaysia (9M), for instance, is famous for its many peninsular islands such as those in the Sabah’s Coastal Islands IOTA group (OC-133) which include Sibuan, Mataking, Sipadan and many others.

Others include Greenland (OX) (NA-018), Long Island (NA-055), Sable Island  (CY0) (NA-063), Barbados (8P) (NA-021), Trinidad (9Y, 9Z) (SA-011), Great Britain (EU-005), Ireland (EI, EJ) (EU-115), Sicily (I*9) (EU-025), Sumatra (OC-143), Borneo (OC-088), Java (OC-021), New Guinea (OC-034), Tasmania (VK7) (OC-006) and Australia’s third largest island, Kangaroo, in the South Australia State East Centre IOTA group (OC-139).

Micro-continental Islands

Some ham islomaniacs find mouth-watering appeal in a subgroup of continental islands referred to as ‘Micro-continental’ islands.  These are formed when a chunk of the landmass separates from the continent.

Examples include Madagascar (5R, 5S) (AF-013), Socotra (Suqutra) (7O) (AF-028), the North (OC-036) and South (OC-134) islands of New Zealand (ZL, ZM), New Caledonia (FK), Kerguelen Islands (FT8X) (AF-048) in the southern Indian Ocean and some of the magnificent Seychelles (S7) islands too.

The DXCC Juan de Nova Island (FT/J) is also a micro-continental island and sits at number 10 on the most wanted DXCC list.


Filling a number of places in the “MOST Wanted DXCC List’ (Heard Island, South Sandwich Islands, Amsterdam and St Paul Islands, Kingman Reef), Oceanic Islands aren’t attached to any continental mass but are instead the result of either coral deposits or volcanic ejections.  It is said that most oceanic islands originated from ancient volcanic activity and have formed along the limits of tectonic plates.

The island arcs of Japan (JA, JS) and the Philippines (DU, DZ) which comprise many RSGB IOTA groups, and slightly fewer than 14 000 islands between them, are evidence of this process.

Volcanic islands like Tristan da Cunha (ZD9) (AF-029) and the island of Surtsey in the Vestmannaeyjay (Westman Islands) IOTA group (EU-071) are created by ‘hot spots’.  Magma rises up and spews lava onto the sea floor from deep within the earth’s mantle.  Over time, this builds up and surfaces above the sea to form an island volcano.  Tectonic plates eventually move the volcano away from the hot spot, essentially cutting off its supply of magma and thus forming an island.

Other examples include the arc-shaped archipelago of 15 volcanic mountains in the north-western Pacific known as the Mariana Islands (KH0) (OC-086), the Aleutian Islands (KL) with their 57 volcanoes, most of Tonga (A3) (OC-049) in the South Pacific Ocean and the South Sandwich Islands (VP8, LU) in the Atlantic.

Another type of volcanic oceanic island occurs where an oceanic ‘rift’ reaches the surface.  Iceland (TF) (EU-021), which is the world’s second largest volcanic island and the Arctic Ocean’s Jan Mayen (JX) (EU-022) are 2 examples.

Coral Islands (Includes atolls and cays)

Arguably the most alluring of contacts for island hunters, and the most elusive, these oceanic islands are formed by coral building sea organisms known as ‘polyps’.  Polyps are known to protect their bodies by constructing limestone walls around themselves which, over time, these colonies grow large enough to form reefs which become the basis for islands.

Reefs become islands when the land beneath the reef rises or the sea level drops around the reef.  Sand, dust and other materials then accumulate on the exposed reef, eventually forming an island.  Well-known coral islands are found in the Florida Keys (W4) (NA-062), Zanzibar (5H) (AF-032) and in the Great Bahama Bank IOTA group (C6) (NA-001).

Also part of the coral island sub-type, atolls are islands formed from a coral reef that has grown on an eroded and submerged volcanic island.  The reef rises to the surface of the water and forms a new island which is typically ring-shaped with a central lagoon.

As reef-building corals thrive only in warm  tropical  and subtropical waters of oceans and seas, most of the world’s atolls are in the Pacific Ocean, with concentrations in the Tuamotu Islands (FO) (OC-066), Caroline Islands, Ratak Chain (OC-029) (V7), Coral Sea Islands, the island groups of Kiribati, Tuvalu (T2) (OC-015), Tokelau (ZK3) (OC-048), Maldives (AS-013), Laccadive Islands (Lakshadweep Islands, AS-011), Chagos Archipelago (VQ9) and Amirante Islands IOTA group (AF-033) of which includes Alphonse and Desroches.

The 8 atolls that belong to the Colombian department of San Andres and Providencia (HK0) (NA-033) east of Nicaragua (YN), are the only atolls found in the Atlantic Ocean.

Cays (also called cayes or keys) are small, low-elevation, sandy islands formed on the surface of a coral reef.  Cays occur in tropical environments throughout the Pacific, Atlantic and Indian Oceans, where they provide habitable and agricultural land for hundreds of thousands of people.  Their surrounding reef ecosystems also provide food and building materials for island inhabitants.

Examples of cays include Warraber in the Torres Strait Islands IOTA group (OC-138) between Australia’s Cape York Peninsula and Papua New Guinea (P2), and Heron Island in the Queensland State (South Coast) Centre IOTA group (OC-142).

By articulating a ham islomaniac’s preferences, I hope this article has provided a more clearer understanding of what most islomaniacs would term, their “drug of choice’.  While island hunters, DXpeditioners and the like share a fascination for all types of islands, most will confess to experiencing an ‘absolute irresistibility’ for a select few.

Whether it’s the ring-shaped coral atolls of the Gilberts, for example, which have grown on eroded and submerged volcanic islands, the micro-continental islands like Madagascar that have split from the mainland, or the smouldering volcanic island arcs such as the Kurils that stretch for approximately 1300 km through the Pacific Ring of Fire, different types and subtypes of islands provide the islomaniac his compulsively sought dose of island magic.

Other terms used by Islomaniacs to describe islands include:

  • Archipelago – A grouping of geographically or geologically related islands
  • Islet – a very small island
  • Holm or Holmen – a common suffix in Nordic and northern European countries
  • -hou – in the Channel Islands
  • Inches – a term used in Scotland and Ireland
  • Skerries – a term used in Ireland
  • Motu – Used to describe the coral-rubble islets common to Polynesia,
  • Aits – Small islands are known as this in and around the River Thames in England
  • Rock – A “rock”, in the sense of a type of islet, is a landform composed of rock, lying offshore, uninhabited, and having at most minimal vegetation.
  • Sandbar – An exposed sandbar is another type of islet
  • Sea stack – A thin, vertical land form jutting out of a body of water
  • Tidal Islands – Small islands which lie off the mainland of an area, being connected to it in low tide and isolated in high tide.
  • River Island – A small islet within the current of a river
  • Ait or eyot – A term for river islands that occur within the River Thames in England
  • Artificial islands