Good question Alex. I just don't think that there really is a definitive really 'bad boy' ocean out there as they all can be pretty unforgiving at times and have nasty reputations (like the 'Southern Ocean').
Even though I have only a tiny resume when it comes to sailing on ocean waters in small boats (< 100') I have some friends who became merchant seamen. From them I learned about Plimsoll marks or load lines where merchant ships are marked with permanent lines on the hull to delineate how much cargo a ship could carry on the course (and waters) they were intending. These marks on commercial ships were universally adopted by all maritime nations around 1900 and are brought to you by your friends in the insurance industry who were remarkably concerned with the cargo (and to some extent the crew) that a ship was carrying. They wanted their cargo delivered safely if it could be done.
The lowest (meaning: least amount of cargo allowed to be loaded) of the Plimsoll Marks is 'WNA' (or Winter North Atlantic) which probably gives the North Atlantic a nod for the worst of the bad boy oceans but - given the Euro-centric nature of the time all of this was implemented I am going to guess that the WNA Plimsoll mark is also observed for many of the other 'bad boy' oceans out there - especially in our summer when the 'Southern Ocean' is in her worst or winter phase.
From Wikipedia:
Standard load line marks
Load Line Mark and Lines and Timber Load Line Mark and Lines for power driven merchant vessels
Load Line Mark and Lines for commercial sailing vessels
The original "Plimsoll Mark" was a circle with a horizontal line through it to show the maximum draft of a ship. Additional marks have been added over the years, allowing for different water densities and expected sea conditions.
Letters may also appear to the sides of the mark indicating the classification society that has surveyed the vessel's load line. The initials used include AB for the American Bureau of Shipping, LR for Lloyd's Register, GL for Germanischer Lloyd, BV for Bureau Veritas, IR for the Indian Register of Shipping, RI for the Registro Italiano Navale and NV for Det Norske Veritas. These letters should be approximately 115 millimetres in height and 75 millimetres in width.[4] The Scantling length is usually referred to during and following load line calculations.
The letters on the Load line marks have the following meanings:
* TF – Tropical Fresh Water
* F – Fresh Water
* T – Tropical Seawater
* S – Summer Temperate Seawater
* W – Winter Temperate Seawater
* WNA – Winter North Atlantic
Fresh water is considered to have a density of 1000 kg/m³ and sea water 1025 kg/m³. Fresh water marks make allowance for the fact that the ship will float deeper in fresh water than salt water. A ship loaded to her Fresh Water mark in fresh water will float at her Summer Mark once she has passed into sea water. Similarly if loaded to her Tropical Fresh water mark she will float at her Tropical Mark once she passes in to sea water.
The Summer load line is the primary load line and it is from this mark that all other marks are derived. The position of the summer load line is calculated from the Load Line Rules and depends on many factors such as length of ship, type of ship, type and number of superstructures, amount of sheer, bow height and so on. The horizontal line through the circle of the Plimsoll mark is at the same level as the summer load line.
The Winter load line is one forty-eighth of the summer load draft below the summer load line.
The Tropical load line is one forty-eighth of the summer load draft above the summer load line.
The Fresh Water load line is an amount equal to \tfrac{\triangle}**40T} millimetres above the summer load line where \triangle is the displacement in metric tonnes at the summer load draft and T is the metric tonnes per centimetre immersion at that draft.
In any case where \triangle cannot be ascertained the fresh water load line is at the same level as the tropical load line.
The position of the Tropical Fresh load line relative to the tropical load line is found in the same way as the fresh water load line is to the summer load line.
The Winter North Atlantic load line is used by vessels not exceeding 100 metres in length when in certain areas of the North Atlantic Ocean during the winter period. When assigned it is 50 millimetres below the winter mark.
See for yourself though:
Waterline - Wikipedia, the free encyclopedia