Like many Garmin items this unit is waterproof to IEC 529 IPX7 specs. (basically can be submerged for 30 minutes at 3 meters with out damage). I would not want to try dunking it but it is good to know. I will highlight the main features I think are useful to this unit but since it has so many features I strongly suggest reading the details provided by Garmin on their web site www.garmin.com. You can also download the user manual in PDF format. If serious about buying any GPS I would suggest doing this so you can really know how it works and its capabilities. The user manual is also does an excellent job describing how GPS and sounders work. If you are new to GPS, you will learn the basic principals of GPS systems and how they work. I also suggest looking into GPS City's free GPS message board where you can ask questions and do some research.

http://www.gpscity.com/cgi-bin/discuss/ultimatebb.cgi.

The 188C display is bright, clear and legible in all types of light(my boat has an open cockpit). The display offers many views of navigation and sounding information and useful split screen capability when you want to have several presentations of information at once.

This review is is written in two parts 1st part covers Navigation(GPS) and the second part covers Fishfinding.

The 188C is both a GPS and Fishfinder in one unit. If your boat has limited room this capability will keep things uncluttered. The screen can display many different types of information in split or full screen. For navigation the 5.0 inch diagonal display large enough for operating the boat and looking at the information presented. The easy to use zoom function allows the user to easily display a useful level of detail. There is also an autozoom feature which also works well. The charts are loaded into the 188 from CD(requires optional blank memory chip) or on preprogrammed chips. If you use the CD method there are 2 ways to accomplish loading map data. One is to connect your PC to the GPS via a special serial cable(optional item). This method is very slow but works well. The other method is to load the data into a USB chip programmer adapter(also an option). Both methods require a blank memory chip. The memory chips are Garmin proprietary. The come in 8, 16, 32, 64 and 128 MB. If you will be navigating across regions on a regular basis you might want to consider a larger chip so you can load more than one region. Keep in mind that there is a huge amount of data on the charts. The CD comes with a code to unlock one region. To use other regions you will need to purchase the unlock codes for more regions. I suggest going to the Garmin website for more information on the level of detail and areas covered before deciding what to buy. If you are like me and only plan to travel within one region you may decide to get the preprogrammed chip. This option is less costly if you only need one region and gives you the identical chart data. If you need multiple regions the CD method is more cost effective. I would still suggest getting the optional PC/Power cable anyway. This allows you to run the 188 on AC power and set things up and play with the unit before heading out to sea. It is also needed to update firmware released by Garmin. These updates fix minor problems and may also add features. On the 188 I bought was on version 4.03 and the update to version 5.0 added many useful features. I did the same thing with the street pilot as well. These things are often ignored, but I think it is worth doing.

Map detail is the same as you would find on nautical charts.
If you want better accuracy you can go for the optional DGPS receiver. I have been using it without the optional receiver and find it accurate enough for my needs.
One nice feature is the Man Over Board key. It is a one touch method to set a waypoint in an emergency and sets the course to route back to that location. I hope I never need this feature but I am glad it is there.

The 188 has alarms based on System, Navigation, and Sonar.
The 188 is a full featured Chartplotter so you can setup your travel plan in detail and get details/track your movement.
The NMEA Interface allows you to interface the GPS with a radio or autopilot.
Again, The best way to understand the units features and operation is to read the PDF file for the 188 on Garmin's site.
The sonar capabilities of the 188 are amazing and full featured. The images are clear and easy to understand. The 188C uses colors to determine bottom hardness. The system can be set to Salt or Fresh water as sound waves travel differently.
Depending on which transponder you select the unit will provide water speed, temperature, and of course soundings. I find the water temperature and water speed functions very useful. If you are boating in stagnant water like a lake this may be less important.
A major feature of the 188C is Thermoclines which identifies breaks in the water where temperature changes more rapidly. This can be of major importance when looking for fish.
The user manual is well written for all levels of users. It explains the technology used and how it works. This is essential for getting the most out of the 188C. Garmin support is responsive and helpful.



Recommended:
Yes

Amount Paid (US$): 1200
Primary Location of Use: Inshore waters and bays
Primary Type of Use: All-around recreation
Length of Boat: 20-25 feet