The Icom IC-M88 handheld VHF marine radio is a good choice for use in a canoe or kayak. It is very small, small enough to fit in most pockets, quite light, has excellent battery life, is ruggedly constructed, and is completely waterproof. It has the standard 5 / 1 watt power options, and an extensive feature set, including multiple scan modes, weather alert function, and self checking function. However, the small size and substantial Li-Ion battery combine to create one of the radios drawbacks: It does not float if dropped overboard. I use the wrist strap to tether the radio to a small D-ring located inside the radio pocket of my PFD. This keeps it secure while still allowing convenient use of the radio, and keeps it with me should I become separated from my kayak.
The other drawback, at least for me, is the lack of a dedicated squelch knob. Instead it has a two-button operated squelch, with 11 possible settings ("open" and 10 "squelch" levels). In fairness, this setup is quite common among currently available waterproof handhelds. Very few have the traditional squelch knob anymore.
Finally, this radio is a bit pricier than most other waterproof handheld marine VHF radios. Whether this extra cost is justified or not, I can't say, since I have only limited experience with other similar radios. But I can say that my IC-M88 has seen much use, and some occasional accidental abuse, over the 5+ years I have owned it, and still looks and operates just like it did the day I bought it.