1   RIDGE
2   BASIN
3   ISLAND
4   ISLANDS
5   TRENCH
6   FRACTURE ZONE
7   TROUGH
8   BANK
9   ARCHIPELAGO
10  PLATEAU
11  RISE
12  SEAMOUNT
13  SEAMOUNTS
14  SEA
15  ABYSSAL PLAIN
16  SEAMOUNT CHAIN
17  DEEP
18  RIDGE COMPLEX
19  MAGNETIC ANOMALY
20  GUYOT
21  PASSAGE
22  SCARP
23  FAN
24  ESCARPMENT
25  TRIPLE JUNCTION
26  SPREADING DISCONTINUITY
27  FRACTURE
28  FOSSIL RIDGE