Well, once you specify beach and around/in salt water, a waterproof unit is a must, so that narrows it down quite a bit. Next, if you are also stating it will be used on land, then a pulse induction (PI) unit is probably a poor choice too.
So, of the waterproof, non-PI units out there that are the choice of most who hunt salt beaches and in the water, there are:
The Minelab Excaliber
Whites Beach Hunter ID 300
Fisher CZ-21
Tesoro Tiger Shark ( which most will say is not very good in salt water but possibly the top of the line in freshwater)
Detector Pro Wader
I may have missed a few, but do some research on the features of each, the coil options if applicable and search the forums for posts on the pros/cons and what people think of them. Also, search the internet on the field tests. Although most if not all field tests accentuate only the positives of the machines, they do point out the features and give the reader a general idea of how the detector works.
I have used the Excal....great machine but a little too heavy for me. The Excal is the only one listed that has automatic ground tracking. The others have manual ground balancing except the Wader, which has a pre-set ground balance. It has multiple tone ID in discriminate mode as well as a nulling feature where iron targets cut off the threshold sound.
I have the Beach Hunter ID 300 and Wader and like them both. The BHID300 has some features that the others do not, specifically the ability to visually ID targets of different conductive properties, in all metal mode, by red, yellow and green lights. The Wader is a cool unit...the guts are in the head phones which make it a very lightweight, easy to use unit. It may not be the deepest of the others, but it's one of the most fun units to use that I have and is really hot on silver.
Never used a Tiger Shark but I do have a Fisher CZ6a which is similar in function to the CZ-21 but not water proof, and it's one of my favorite detectors. BUT..its a different breed because of the options it has.
If I had to buy another waterproof machine right now, I would probably opt for the Excal II with the 8 inch coil. With the 8 inch coil, you can use it in parks, playgrounds and other areas where you will be coin/jewelry hunting on land.
I hunt salt beaches almost exclusively, but if I ever end up venturing into the fresh water scene I would buy a Tiger Shark in a second since I never owned one and love Tesoros dedication to it's customers, it's service and their machines are great.
One last thing...not sure if you will ever be diving, and if so, you need to check the depth ratings of these. The Wader is the unit that has the least depth rating at only 6 feet..I believe the BHID300 is rated at 25 feet, while the others I believe are at least 100 feet.
Its a very hard question to answer, and the best thing by far is to do research and if at all possible, see if there are any local dealers or detecting clubs in your area where you can see first hand the detectors, how they feel and if possible how they hunt.
