WaterProof..  Submersible.. Spray proof..  What DO these terms mean?

MIL-STD 810 Immersion Standard, Military Specification equipment
MIL-STD 810 Blowing Rain,  Military Specification equipment
JIS 2-8  Japanese Water Protection Specs similar to IEC529
CFR Title 46 Part 110.15  Aircraft Civilian specifications
IEC 529 European (ECC) water protection specifications

Of these, only IEC 529 (European Community Specification) and JIS2-8 (Japanese Industry Standard) have graduated test levels.  These two specifications are very similar, but IEC 529 is gaining more acceptance in Europe which is a major market for many US manufacturers and is more defined in terms of the actual test.   The table below gives a summary of the requirements for IEC 529 for WATER PROTECTION PROVISIONS.

Level         Definition
0           Non protected,  No special protection
1           Protected against falling water Equivalent to 3-5mm rainfall per minute for a duration of 10 minutes.
                        Unit is placed in its normal operating position.
2           Protected against falling water when tilted up to 15 degrees.   Same as (1) above but unit is tested
                        in 4 fixed positions - tilted 15 degree in each direction from normal operating position.
3       Protected against spraying water,   Water spraying up to 60 degrees from vertical at 10 liters/min at
                        a gage  pressure of 80-100kN/m2 for 5 min.
4       Protected against splashing water.      Same as level 3 but water is sprayed at all angles.
5       Protected against water jets    Water projected at all angles through a 6.3mm nozzle at a flow rate of
                       12.5 liters/min at a gage pressure of 30kN/m2 for 3 minutes from a distance of 3 meters.
6       Protected against heavy seas.     Water projected at all angles through a 12.5mm nozzle at a flow rate
                        of 100 liters/min at a gage pressure of 100kN/m2 for 3 minutes from a distance of 3 meters.
7       Protected against water immersion.       Immersion for 30 minutes at a depth of 1 meter.
8       Protected against water submersion      The equipment is suitable for continuos submersion in water
                        under conditions which are identified by the manufacturer.
*Note: IEC 529 level 7 is designated "IPX7" and is equivalent to JIS 7.  The position of "X" being left blank indicates that the unit has no special mechanical protection.
*Note:  Garmin typically uses the IEC-529 spec for the design spec for water protection level for their line of GPS equipment.  Marine rated GPS equipment is usually tested to IPX7.

Lowrance uses different methodology which are non standard but is roughly equivalent to IPX7 but at 2ft depth for 1 hour .  Magellan's immersion standards are not known to us at this time.